Systems and methods with variable mitigation thresholds

ABSTRACT

An indoor air quality (IAQ) system for a building includes an IAQ sensor that is located within the building and that is configured to measure an IAQ parameter. The IAQ parameter is one of: an amount of particulate of at least a predetermined size present in air; an amount of volatile organic compounds (VOCs) present in air; and an amount of carbon dioxide present in air. A mitigation module is configured to: selectively turn on a mitigation device based on a comparison of the IAQ parameter with a first ON threshold and a second ON threshold; and selectively turn off the mitigation device based on a comparison of the IAQ parameter with an OFF threshold. A clean module is configured to determine a clean value for the IAQ parameter. A thresholds module is configured to, based on the clean value, determine the first ON threshold and the OFF threshold.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation and claims the benefit of U.S.application Ser. No. 17/048,982 filed on Oct. 19, 2020, a 371 ofInternational Application PCT/US2019/028408, filed on Apr. 19, 2019 andU.S. Provisional Application No. 62/660,354, filed on Apr. 20, 2018. Theentire disclosure of the application referenced above is incorporatedherein by reference.

FIELD

The present disclosure relates to environmental control systems and moreparticularly to indoor air quality control systems and methods.

BACKGROUND

The background description provided here is for the purpose of generallypresenting the context of the disclosure. Work of the presently namedinventors, to the extent it is described in this background section, aswell as aspects of the description that may not otherwise qualify asprior art at the time of filing, are neither expressly nor impliedlyadmitted as prior art against the present disclosure.

A residential or light commercial HVAC (heating, ventilation, and/or airconditioning) system controls temperature and humidity of a building.Upper and lower temperature limits may be specified by an occupant orowner of the building, such as an employee working in the building or ahomeowner.

A thermostat controls operation of the HVAC system based on a comparisonof the temperature at a thermostat and the target values. The thermostatmay control the HVAC system to heat the building when the temperature isless than the lower temperature limit. The thermostat may control theHVAC system to cool the building when the temperature is greater thanthe upper temperature limit. Heating the building and cooling thebuilding generally decreases humidity, although the HVAC system mayinclude a humidifier that adds humidity to warm air output by the HVACsystem during heating of the building.

SUMMARY

In a feature, an indoor air quality (IAQ) system for a building isdescribed. An IAQ sensor is located within the building and isconfigured to measure an IAQ parameter, the IAQ parameter being one of:an amount of particulate of at least a predetermined size present inair; an amount of volatile organic compounds (VOCs) present in air; andan amount of carbon dioxide present in air. A mitigation module isconfigured to: selectively turn on a mitigation device based on acomparison of the IAQ parameter with a first ON threshold and a secondON threshold; and selectively turn off the mitigation device based on acomparison of the IAQ parameter with an OFF threshold. A clean module isconfigured to determine a clean value for the IAQ parameter. Athresholds module is configured to, based on the clean value, determinethe first ON threshold and the OFF threshold.

In further features, the thresholds module is configured to set thefirst ON threshold based on the clean value plus a first predeterminedvalue.

In further features, the thresholds module is configured to set thesecond ON threshold to a fixed predetermined value.

In further features, the thresholds module is configured to set the OFFthreshold based on a second predetermined value plus a greater one ofthe first and second ON thresholds.

In further features, the mitigation module is configured to turn on themitigation device in response to a determination that the IAQ parameteris greater than both of the first ON threshold and the second ONthreshold.

In further features, the mitigation module is configured to turn off themitigation device when both (i) the IAQ parameter is less than the OFFthreshold and (ii) at least one OFF condition is satisfied.

In further features, the mitigation module is configured to turn off themitigation device when both (i) the IAQ parameter is less than the OFFthreshold and (ii) the IAQ parameter is less than or equal to the cleanlevel.

In further features, the mitigation module is configured to turn off themitigation device when both (i) the IAQ parameter is less than the OFFthreshold and (ii) a slope of the IAQ parameter is within apredetermined amount of zero.

In further features, the mitigation module is configured to turn off themitigation device when both (i) the IAQ parameter is less than the OFFthreshold and (ii) a predetermined period has passed since the IAQparameter became less than the OFF threshold.

In further features, the IAQ parameter is the amount of particulate, andthe IAQ system further includes a time to capacity module configured todetermine the predetermined period by solving the following equation forperiod:

${\left( \frac{Clean}{Peak} \right) = \left( {1 - {\frac{afr}{vol}*{efficiency}}} \right)^{period}},$where period is the predetermined period, Clean is the clean value, Peakis a peak value of the amount of particulate, afr is an air flow rate ofa blower of an air handler unit of the building, vol is a volume ofinterior space the building, and efficiency is an efficiency of a filterof the air handler unit.

In further features, the IAQ parameter is one of (i) the amount of VOCsand (ii) the amount of carbon dioxide, and the IAQ system furtherincludes a time to capacity module configured to determine thepredetermined period by solving the following equation for period:

${\left( \frac{Clean}{Peak} \right) = \left( {1 - {\frac{afr}{vol}*{percentage}}} \right)^{period}},$where period is the predetermined period, Clean is the clean value, Peakis a peak value of the one of (i) the amount of VOCs and (ii) the amountof carbon dioxide, afr is an air flow rate of a ventilator of thebuilding, vol is a volume of interior space the building, and percentageis a percentage of the volume of the building that the ventilator willcirculate out of the building per minute.

In a feature, an indoor air method (IAQ) method includes: by an IAQsensor that is located within a building, measuring an IAQ parameter,the IAQ parameter being one of: an amount of particulate of at least apredetermined size present in air; an amount of volatile organiccompounds (VOCs) present in air; and an amount of carbon dioxide presentin air; selectively turning on a mitigation device based on a comparisonof the IAQ parameter with a first ON threshold and a second ONthreshold; selectively turning off the mitigation device based on acomparison of the IAQ parameter with an OFF threshold; determining aclean value for the IAQ parameter; and based on the clean value,determining the first ON threshold and the OFF threshold.

In further features, determining the first ON threshold includes settingthe first ON threshold based on the clean value plus a firstpredetermined value.

In further features, the IAQ method further includes setting the secondON threshold to a fixed predetermined value.

In further features, determining the OFF threshold includes setting theOFF threshold based on a second predetermined value plus a greater oneof the first and second ON thresholds.

In further features, selectively turning on the mitigation deviceincludes turning on the mitigation device in response to a determinationthat the IAQ parameter is greater than both of the first ON thresholdand the second ON threshold.

In further features, selectively turning off the mitigation deviceincludes turning off the mitigation device when both (i) the IAQparameter is less than the OFF threshold and (ii) at least one OFFcondition is satisfied.

In further features, selectively turning off the mitigation deviceincludes turning off the mitigation device when both (i) the IAQparameter is less than the OFF threshold and (ii) the IAQ parameter isless than or equal to the clean level.

In further features, selectively turning off the mitigation deviceincludes turning off the mitigation device when both (i) the IAQparameter is less than the OFF threshold and (ii) a slope of the IAQparameter is within a predetermined amount of zero.

In further features, selectively turning off the mitigation deviceincludes turning off the mitigation device when both (i) the IAQparameter is less than the OFF threshold and (ii) a predetermined periodhas passed since the IAQ parameter became less than the OFF threshold.

In further features, the IAQ parameter is the amount of particulate, andthe IAQ method further includes determining the predetermined period bysolving the following equation for period:

${\left( \frac{Clean}{Peak} \right) = \left( {1 - {\frac{afr}{vol}*{efficiency}}} \right)^{period}},$where period is the predetermined period, Clean is the clean value, Peakis a peak value of the amount of particulate, afr is an air flow rate ofa blower of an air handler unit of the building, vol is a volume ofinterior space the building, and efficiency is an efficiency of a filterof the air handler unit.

In further features, the IAQ parameter is one of (i) the amount of VOCsand (ii) the amount of carbon dioxide, and the IAQ method furtherincludes determining the predetermined period by solving the followingequation for period:

${\left( \frac{Clean}{Peak} \right) = \left( {1 - {\frac{afr}{vol}*{percentage}}} \right)^{period}},$where period is the predetermined period, Clean is the clean value, Peakis a peak value of the one of (i) the amount of VOCs and (ii) the amountof carbon dioxide, afr is an air flow rate of a ventilator of thebuilding, vol is a volume of interior space the building, and percentageis a percentage of the volume of the building that the ventilator willcirculate out of the building per minute.

In a feature, an indoor air quality (IAQ) system for a building isdescribed. A particulate sensor is located within the building and isconfigured to measure an amount of particulate of at least apredetermined size present in air. A mitigation module is configured to:selectively turn on a blower of an air handler unit of the buildingbased on a comparison of the amount of particulate with an ON threshold;and selectively turn off the blower based on a comparison of the amountof particulate with an OFF threshold. A timer module is configured tomeasure a period between a first time when the mitigation module turnedthe blower ON and a second time when the mitigation module next turnedthe blower OFF. A time to capacity module is configured to determine anexpected period of the blower being ON for a mitigation event when afilter of the air handler unit is new by solving the following equationfor period:

${\left( {{Later}/{Initial}} \right) = \left( {1 - {\frac{afr}{vol}*{efficiency}}} \right)^{period}},$where period is the expected period, Later is the amount of particulatemeasured by the particulate sensor at the second time, Initial is theamount of particulate measured by the particulate sensor at the firsttime, afr is an air flow rate of the blower of the air handler unit, volis a volume of interior space the building, and efficiency is anefficiency of the filter when new. A diagnostic module is configured toselectively generate an indicator to replace the filter based on acomparison of the period and the expected period.

In further features, the diagnostic module is configured to generate theindicator to replace the filter when the period is greater than theexpected period by at least a predetermined amount.

In further features, the diagnostic module is configured to generate theindicator to replace the filter when the period is at least twice aslong as the expected period.

In further features, the diagnostic module is configured to generate theindicator to replace the filter when the period is at least three timesthe expected period.

In further features, the diagnostic module is configured to determine anamount that the filter is filled with particulate matter based on acomparison of the period and the expected period and to generate theindicator to replace the filter based on the amount that the filter isfilled.

In further features, the diagnostic module is configured to display theindicator to replace the filter on a display of a customer deviceassociated with the building.

In a feature, an indoor air quality (IAQ) method includes: by aparticulate sensor that is located within a building, measuring anamount of particulate of at least a predetermined size present in air;selectively turning on a blower of an air handler unit of the buildingbased on a comparison of the amount of particulate with an ON threshold;selectively turning off the blower based on a comparison of the amountof particulate with an OFF threshold; measuring a period between a firsttime when the blower was turned ON and a second time when the blower isnext turned OFF; determining an expected period of the blower being ONfor a mitigation event when a filter of the air handler unit is new bysolving the following equation for period:

${\left( {{Later}/{Initial}} \right) = \left( {1 - {\frac{afr}{vol}*{efficiency}}} \right)^{period}},$where period is the expected period, Later is the amount of particulatemeasured by the particulate sensor at the second time, Initial is theamount of particulate measured by the particulate sensor at the firsttime, afr is an air flow rate of the blower of the air handler unit, volis a volume of interior space the building, and efficiency is anefficiency of the filter when new; and selectively generating anindicator to replace the filter based on a comparison of the period andthe expected period.

In further features, selectively generating the indicator includesgenerating the indicator to replace the filter when the period isgreater than the expected period by at least a predetermined amount.

In further features, selectively generating the indicator includesgenerating to replace the filter when the period is at least twice aslong as the expected period.

In further features, selectively generating the indicator includesgenerating the indicator to replace the filter when the period is atleast three times the expected period.

In further features, the IAQ method further includes determining anamount that the filter is filled with particulate matter based on acomparison of the period and the expected period, where selectivelygenerating the indicator includes generating the indicator to replacethe filter based on the amount that the filter is filled.

In further features, the IAQ method further includes displaying theindicator to replace the filter on a display of a customer deviceassociated with the building.

In a feature, an indoor air quality (IAQ) system for a building isdescribed. An IAQ sensor is located within the building and isconfigured to measure an IAQ parameter, the IAQ parameter being one of:an amount of particulate of at least a predetermined size present inair; an amount of volatile organic compounds (VOCs) present in air; andan amount of carbon dioxide present in air. A mitigation module isconfigured to: selectively turn on a mitigation device based on acomparison of the IAQ parameter with an ON threshold; and selectivelyturn off the mitigation device based on a comparison of the IAQparameter with an OFF threshold. A timer module is configured to measurea period for a mitigation event between a first time when the mitigationmodule turned the mitigation device ON and a second time when themitigation module next turned the mitigation device OFF. An event moduleis configured to determine an event classification for the mitigationevent based on the period and to store the event classification inmemory.

In further features, a time to capacity module is configured todetermine an expected period for the mitigation event by solving thefollowing equation for period:

${\left( {{Later}/{Initial}} \right) = \left( {1 - {\frac{afr}{vol}*{efficiency}}} \right)^{period}},$where period is an expected period, Later is the amount of particulatemeasured by the particulate sensor at the second time, Initial is theamount of particulate measured by the particulate sensor at the firsttime, afr is an air flow rate of a blower of an air handler unit of thebuilding, vol is a volume of interior space the building, and efficiencyis an efficiency of a filter of the air handler unit when new, and theevent module is configured to determine the event classification furtherbased on the expected period.

In further features, the event module is configured to set the eventclassification to a first classification when the period is greater thanthe expected period.

In further features, the event module is configured to set the eventclassification to a second classification when the period is less thanthe expected period.

In further features, the event module is configured to set the eventclassification to: a first classification when the period is less than afirst predetermined period; a second classification when the period isgreater than a second predetermined period that is greater than thefirst predetermined period; and a third classification when the periodis greater than the first predetermined period and less than the secondpredetermined period.

In further features, a time to capacity module is configured todetermine an expected period for the mitigation event by solving thefollowing equation for period:

${\left( {{Later}/{Initial}} \right) = \left( {1 - {\frac{afr}{vol}*{percentage}}} \right)^{period}},$where period is the expected period, Later is a first value of the IAQparameter at the second time, Initial is a second value of the IAQparameter at the first time, afr is an air flow rate of the mitigationdevice, vol is a volume of interior space the building, and percentageis a percentage of the volume of the building that the mitigation devicewill circulate out of the building per minute, and the event module isconfigured to determine the event classification further based on theexpected period.

In further features, the event module is configured to set the eventclassification to a first classification when the period is greater thanthe expected period.

In further features, the event module is configured to set the eventclassification to a second classification when the period is less thanthe expected period.

In a feature, an indoor air quality (IAQ) method includes: by an IAQsensor that is located within a building, measuring an IAQ parameter,the IAQ parameter being one of: an amount of particulate of at least apredetermined size present in air; an amount of volatile organiccompounds (VOCs) present in air; and an amount of carbon dioxide presentin air; selectively turning on a mitigation device based on a comparisonof the IAQ parameter with an ON threshold; selectively turning off themitigation device based on a comparison of the IAQ parameter with an OFFthreshold; measuring a period for a mitigation event between a firsttime when mitigation device was turned ON and a second time when themitigation device was next turned OFF; determining an eventclassification for the mitigation event based on the period; and storingthe event classification in memory.

In a feature, the IAQ method further includes determining an expectedperiod for the mitigation event by solving the following equation forperiod:

${\left( {{Later}/{Initial}} \right) = \left( {1 - {\frac{afr}{vol}*{efficiency}}} \right)^{period}},$where period is an expected period, Later is the amount of particulatemeasured by the particulate sensor at the second time, Initial is theamount of particulate measured by the particulate sensor at the firsttime, afr is an air flow rate of a blower of an air handler unit of thebuilding, vol is a volume of interior space the building, and efficiencyis an efficiency of a filter of the air handler unit when new, wheredetermining the event classification includes determining the eventclassification further based on the expected period.

In further features, determining the event classification includessetting the event classification to a first classification when theperiod is greater than the expected period.

In further features, determining the event classification includessetting the event classification to a second classification when theperiod is less than the expected period.

In further features, determining the event classification includessetting the event classification to: a first classification when theperiod is less than a first predetermined period; a secondclassification when the period is greater than a second predeterminedperiod that is greater than the first predetermined period; and a thirdclassification when the period is greater than the first predeterminedperiod and less than the second predetermined period.

In further features, the IAQ method further includes determining anexpected period for the mitigation event by solving the followingequation for period:

${\left( {{Later}/{Initial}} \right) = \left( {1 - {\frac{afr}{vol}*{percentage}}} \right)^{period}},$where period is the expected period, Later is a first value of the IAQparameter at the second time, Initial is a second value of the IAQparameter at the first time, afr is an air flow rate of the mitigationdevice, vol is a volume of interior space the building, and percentageis a percentage of the volume of the building that the mitigation devicewill circulate out of the building per minute, where determining theevent classification includes determining the event classificationfurther based on the expected period.In further features, determining the event classification includessetting the event classification to a first classification when theperiod is greater than the expected period.In further features, determining the event classification includessetting the event classification to a second classification when theperiod is less than the expected period.

In a feature, an indoor air quality (IAQ) system for a building isdescribed. An IAQ sensor module is located within the building andcomprises at least one of: a temperature sensor configured to measure atemperature of air at the IAQ sensor module; a relative humidity (RH)sensor configured to measure a RH of the air at the IAQ sensor module; aparticulate sensor configured to measure an amount of particulate of atleast a predetermined size present in the air at the IAQ sensor module;a volatile organic compound (VOC) sensor configured to measure an amountof VOCs present in the air at the IAQ sensor module; and a carbondioxide sensor configured to measure an amount of carbon dioxide presentin the air at the IAQ sensor module. At least one of a thermostat and anIAQ control module is configured to, in response to a determination thatone of the temperature, the RH, the amount of particulate, the amount ofVOCs, and the amount of carbon dioxide is greater than a predeterminedvalue while one of a plurality of mitigation devices is off: determinean area between: a baseline value; and a curve formed by the one of thetemperature, the RH, the amount of particulate, the amount of VOCs, andthe amount of carbon dioxide; and selectively turn on the one of theplurality of mitigation devices.

In further features, the mitigation devices include at least two of: anair handler unit of a heating, ventilation, and air conditioning (HVAC)system a blower of an air handler unit of the HVAC system of thebuilding; a condenser unit of the HVAC system of the building; an airpurifier configured to receive power via a standard wall outlet and tofilter particulate from air within the building; a humidifier configuredto humidify air within the building; a dehumidifier configured todehumidify air within the building; and a ventilator configured to ventair out of the building from within the building.

In further features, the at least one of the thermostat and the IAQcontrol module is configured to selectively turn on the one of theplurality of mitigation devices based on the area.

In further features, the at least one of the thermostat and the IAQcontrol module is configured to turn on the one of the plurality ofmitigation devices when the area is greater than a predetermined value.

In further features, the at least one of the thermostat and the IAQcontrol module is configured to maintain the one of the plurality ofmitigation devices off when the area is less than the predeterminedvalue.

In further features, the at least one of the thermostat and the IAQcontrol module is configured to selectively turn on the one of theplurality of mitigation devices when at least two of the temperature,the RH, the amount of particulate, the amount of VOCs, and the amount ofcarbon dioxide are greater than respective predetermined values.

In further features, the at least one of the thermostat and the IAQcontrol module is configured to maintain the one of the plurality ofmitigation devices off when: only one of the temperature, the RH, theamount of particulate, the amount of VOCs, and the amount of carbondioxide is greater than the predetermined value; and the area is lessthan a predetermined value.

In further features, the at least one of the thermostat and the IAQcontrol module is configured to selectively turn on at least one of theplurality of mitigation devices when: at least two of the temperature,the RH, the amount of particulate, the amount of VOCs, and the amount ofcarbon dioxide are greater than respective predetermined values; and thearea is less than a predetermined value.

In further features, the at least one of the thermostat and the IAQcontrol module is further configured to turn on the at least one of theplurality of mitigation devices when the area is greater than thepredetermined value.

In further features, the at least one of the thermostat and the IAQcontrol module is configured to selectively turn on at least one of theplurality of mitigation devices when at least three of the temperature,the RH, the amount of particulate, the amount of VOCs, and the amount ofcarbon dioxide are greater than respective predetermined values.

In a feature, a method includes: at least one of: by a temperaturesensor of an indoor air quality (IAQ) sensor module within a building,measuring a temperature of air at the IAQ sensor module; by a relativehumidity (RH) sensor of the IAQ sensor module within the building,measuring a RH of the air at the IAQ sensor module; by a particulatesensor of the IAQ sensor module within the building, measuring an amountof particulate of at least a predetermined size present in the air atthe IAQ sensor module; by a volatile organic compound (VOC) sensor ofthe IAQ sensor module within the building, measuring an amount of VOCspresent in the air at the IAQ sensor module; and by a carbon dioxidesensor of the IAQ sensor module within the building, measuring an amountof carbon dioxide present in the air at the IAQ sensor module; and inresponse to a determination that one of the temperature, the RH, theamount of particulate, the amount of VOCs, and the amount of carbondioxide is greater than a predetermined value while one of a pluralityof mitigation devices is off: determining an area between: a baselinevalue; and a curve formed by the one of the temperature, the RH, theamount of particulate, the amount of VOCs, and the amount of carbondioxide; and selectively turning on the one of the plurality ofmitigation devices.

In further features, the mitigation devices include at least two of: anair handler unit of a heating, ventilation, and air conditioning (HVAC)system a blower of an air handler unit of the HVAC system of thebuilding; a condenser unit of the HVAC system of the building; an airpurifier configured to receive power via a standard wall outlet and tofilter particulate from air within the building; a humidifier configuredto humidify air within the building; a dehumidifier configured todehumidify air within the building; and a ventilator configured to ventair out of the building from within the building.

In further features, selectively turning on the one of the plurality ofmitigation devices includes selectively turning on the one of theplurality of mitigation devices the one of the plurality of mitigationdevices based on the area.

In further features, selectively turning on the one of the plurality ofmitigation devices includes turning on the one of the plurality ofmitigation devices when the area is greater than a predetermined value.

In further features, the method further includes maintaining the one ofthe plurality of mitigation devices off when the area is less than thepredetermined value.

In further features, selectively turning on the one of the plurality ofmitigation devices includes selectively turning on the one of theplurality of mitigation devices when at least two of the temperature,the RH, the amount of particulate, the amount of VOCs, and the amount ofcarbon dioxide are greater than respective predetermined values.

In further features, maintaining the one of the plurality of mitigationdevices off when: only one of the temperature, the RH, the amount ofparticulate, the amount of VOCs, and the amount of carbon dioxide isgreater than the predetermined value; and the area is less than apredetermined value.

In further features, selectively turning on the one of the plurality ofmitigation devices includes selectively turning on at least one of theplurality of mitigation devices when: at least two of the temperature,the RH, the amount of particulate, the amount of VOCs, and the amount ofcarbon dioxide are greater than respective predetermined values; and thearea is less than a predetermined value.

In further features, the method further includes turning on the at leastone of the plurality of mitigation devices when the area is greater thanthe predetermined value.

In further features, selectively turning on the one of the plurality ofmitigation devices includes selectively turning on at least one of theplurality of mitigation devices when at least three of the temperature,the RH, the amount of particulate, the amount of VOCs, and the amount ofcarbon dioxide are greater than respective predetermined values.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description, the claims and the drawings. Thedetailed description and specific examples are intended for purposes ofillustration only and are not intended to limit the scope of thedisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a block diagram of an example heating, ventilation, and airconditioning (HVAC) system;

FIG. 2A is a functional block diagram of an air handler unit of anexample HVAC system;

FIGS. 2B and 2C are functional block diagrams of example condenser unitsof example HVAC systems;

FIG. 3 is a functional block diagram of an example indoor air quality(IAQ) sensor module that can be used with an HVAC system and/or othermitigation devices;

FIGS. 4A-4C are a functional block diagram of an example IAQ controlsystem;

FIG. 5A is a functional block diagram of an example remote monitoringsystem;

FIG. 5B is a functional block diagram of an example monitoring system;

FIGS. 6-9 are example user interfaces displayed by a user computingdevice during execution of an application based on data received from aremote monitoring system;

FIG. 10 includes a functional block diagram of an example implementationof an IAQ control module;

FIGS. 11-13 include example graphs of an IAQ parameter (e.g., amount ofparticulate, amount of VOCs, or amount of carbon dioxide) over time;

FIGS. 14 and 15 include example graphs of particulate matter (PM) overtime;

FIG. 16 includes a flowchart depicting an example method of controllingmitigation of an IAQ parameter;

FIG. 17 includes a flowchart depicting an example method of indicatingwhether to replace a filter of an air handler unit;

FIG. 18 includes a flowchart depicting an example method of classifyingmitigation events;

FIG. 19 includes an example graph of amount of particulate versusmeasured mitigation period;

FIG. 20 includes an example graph of an amount of VOCs versus measuredmitigation period;

FIG. 21 includes a functional block diagram of an example implementationof a thermostat;

FIG. 22 includes an example graph of particulate, volatile organiccompounds (VOCs), and carbon dioxide (CO2) over time;

FIG. 23 includes an example graph of particulate, VOCs, CO2,temperature, and relative humidity (RH) over time; and

FIG. 24 includes a flowchart depicting an example method of mitigatingIAQ parameters.

In the drawings, reference numbers may be reused to identify similarand/or identical elements.

DETAILED DESCRIPTION

According to the present disclosure, an indoor air quality (IAQ) sensormodule can be used with one or more mitigation devices of a residentialor light commercial HVAC (heating, ventilation, and/or air conditioning)system of a building and/or one or more other mitigation devices. TheIAQ sensor module includes one, more than one, or all of a temperaturesensor, a relative humidity (RH) sensor, a particulate sensor, avolatile organic compound (VOC) sensor, and a carbon dioxide (CO₂)sensor. The IAQ sensor module may also include one or more other IAQsensors, such as occupancy, barometric pressure, light, sound, etc. Thetemperature sensor senses a temperature of air at the location of theIAQ sensor. The RH sensor measures a RH of air at the location of theIAQ sensor. The particulate sensor measures an amount (e.g.,concentration) of particulate greater than a predetermined size in theair at the location of the IAQ sensor. The VOC sensor measures an amountof VOCs in the air at the location of the IAQ sensor. The carbon dioxidesensor measures an amount of carbon dioxide in the air at the locationof the IAQ sensor. Other IAQ sensors would measure an amount of asubstance or condition in the air at the location of the IAQ sensor.

The IAQ sensor module is wirelessly connected to a thermostat of theHVAC system, such as via Bluetooth or WiFi. The IAQ sensor module mayadditionally or alternatively be wirelessly connected to a controlmodule. The IAQ sensor module communicates measurements from itssensors, and optionally, a time and date to the thermostat and/or thecontrol module.

The control module and/or the thermostat can provide information on themeasurements of the IAQ sensor module and other data (e.g., statuses ofmitigation devices, local outdoor air conditions, etc.) to one or moreuser devices (e.g., of tenants, occupants, customers, contractors, etc.)associated with the building. For example, the building may be asingle-family residence, and the customer may be the homeowner, alandlord, or a tenant. In other implementations, the building may be alight commercial building, and the customer may be the building owner, atenant, or a property management company.

The control module and/or the thermostat controls operation of themitigation devices based on the measurements from the IAQ sensor module.For example, the control module and/or the thermostat controls operationof the mitigation devices based on maintaining a temperature measured bythe IAQ sensor module within upper and lower temperature limits, basedon maintaining a RH measured by the IAQ sensor within upper and lower RHlimits, based on maintaining the amount of particulate in the air at theIAQ sensor module below a predetermined amount of particulate, based onmaintaining the amount of VOCs in the air at the IAQ sensor module belowa predetermined amount of VOCs, and/or based on maintaining the amountof carbon dioxide in the air at the IAQ sensor module below apredetermined amount of carbon dioxide.

For example, the control module and/or the thermostat may turn on adehumidifier when the RH is greater than an upper dehumidification RHlimit and maintain the dehumidifier on until the RH becomes less than alower dehumidification RH limit. The control module and/or thethermostat may turn on a humidifier when the RH is less than a lowerhumidification RH limit and maintain the humidifier on until the RHbecomes greater than an upper humidification RH limit. The controlmodule and/or the thermostat may turn on a particulate decreasing device(e.g., an air cleaner/purifier) when the amount of particulate isgreater than an upper particulate limit and maintain the particulatedecreasing device on until the amount of particulate becomes less than alower particulate limit. The control module and/or the thermostat mayturn on a carbon dioxide decreasing device (e.g., a ventilator) when theamount of carbon dioxide is greater than an upper carbon dioxide limitand maintain the carbon dioxide decreasing device on until the amount ofcarbon dioxide becomes less than a lower carbon dioxide limit. Thecontrol module and/or the thermostat may turn on a VOC decreasing device(e.g., a ventilator or an air/cleaner purifier) when the amount of VOCsis greater than an upper VOC limit and maintain the VOC decreasingdevice on until the amount of VOCs becomes less than a lower VOC limit.

The limits may be set to predetermined values by default. The limits,however, may be too high or too low for the building under somecircumstances. The limits being too high or too low may cause over-useof one or more mitigation devices. The control module may thereforeadjust (increase or decrease) one or more of the limits.

Additionally, mitigation of a deviation of one parameter may cause adeviation in another parameter and prompt mitigation of the otherparameter. For example, mitigation of VOCs and/or carbon dioxide maycause an increase in RH within the building as air from within thebuilding is vented to outside of the building and more humid outside airis drawn into the building. If the RH within the building increases togreater than the upper dehumidification RH limit due to the mitigationof VOCs and/or carbon dioxide, the control module and/or the thermostatmay trigger dehumidification. To prevent mitigation of one parameterfrom causing another parameter to be mitigated, the control module mayadjust (increase or decrease) one or more of the limits. Adjusting oneof more of the limits may increase an overall amount of time spent withone or more IAQ parameters between the respective upper and lowerlimits. Stated differently, one or more of the limits may decrease anoverall amount of time spent with one or more IAQ parameters beingmitigated or outside of the respective upper and lower limits.

As used in this application, the term HVAC can encompass allenvironmental comfort systems in a building, including heating, cooling,humidifying, dehumidifying, and air exchanging and purifying, and coversdevices such as furnaces, heat pumps, humidifiers, dehumidifiers,ventilators, and air conditioners. HVAC systems as described in thisapplication do not necessarily include both heating and airconditioning, and may instead have only one or the other.

In split HVAC systems, an air handler unit is often located indoors, anda condensing unit is often located outdoors. In heat pump systems, thefunction of the air handler unit and the condensing unit are reverseddepending on the mode of the heat pump. As a result, although thepresent disclosure uses the terms air handler unit and condensing unit,the terms indoor unit and outdoor unit could be used instead in thecontext of a heat pump. The terms indoor unit and outdoor unit emphasizethat the physical locations of the components stay the same while theirroles change depending on the mode of the heat pump. A reversing valveselectively reverses the flow of refrigerant from what is shown in FIG.1 depending on whether the system is heating the building or cooling thebuilding in a heat pump system. When the flow of refrigerant isreversed, the roles of the evaporator and condenser are reversed—i.e.,refrigerant evaporation occurs in what is labeled the condenser whilerefrigerant condensation occurs in what is labeled as the evaporator.

The control module and/or the thermostat upload data to a remotelocation. The remote location may be accessible via any suitablenetwork, including the Internet. The remote location includes one ormore computers, which will be referred to as servers. The serversexecute a monitoring system on behalf of a monitoring company.Additionally or alternatively, a user computing device may serve as themonitoring system. The monitoring system receives and processes the datafrom the controller and/or thermostat of customers who have such systemsinstalled. The monitoring system can provide performance information,diagnostic alerts, and error messages to one or more users associatedwith the building and/or third parties, such as designated HVACcontractors.

A server of the monitoring system includes a processor and memory. Thememory stores application code that processes data received from thecontroller and/or the thermostat. The processor executes thisapplication code and stores received data either in the memory or inother forms of storage, including magnetic storage, optical storage,flash memory storage, etc. While the term server is used in thisapplication, the application is not limited to a single server.

A collection of servers may together operate to receive and process datafrom multiple buildings. A load balancing algorithm may be used betweenthe servers to distribute processing and storage. The presentapplication is not limited to servers that are owned, maintained, andhoused by a monitoring company. Although the present disclosuredescribes diagnostics and processing and alerting occurring in a remotemonitoring system, some or all of these functions may be performedlocally using installed equipment and/or customer resources, such as ona customer computer or computers.

Customers and/or HVAC contractors may be notified of current andpredicted issues (e.g., dirty filter) affecting effectiveness orefficiency of the HVAC system and/or the mitigating devices, and mayreceive notifications related to routine maintenance. The methods ofnotification may take the form of push or pull updates to anapplication, which may be executed on a smart phone, tablet, anothertype of mobile device, or on a computer (e.g., laptop or desktop).Notifications may also be viewed using web applications or on localdisplays, such as on the thermostat and/or other displays locatedthroughout the building. Notifications may also include text messages,emails, social networking messages, voicemails, phone calls, etc.

Based on measurements from the control module, the thermostat, and/orthe IAQ sensor module, the monitoring company can determine whethervarious components are operating at their peak performance. Themonitoring company can advise the customer and a contractor whenperformance is reduced. This performance reduction may be measured forthe system as a whole, such as in terms of efficiency, and/or may bemonitored for one or more individual components.

In addition, the monitoring system may detect and/or predict failures ofone or more components of the system. When a failure is detected, thecustomer can be notified and potential remediation steps can be takenimmediately. For example, components of the HVAC system may be shut downto prevent or minimize damage, such as water damage, to HVAC components.A contractor can also be notified that a service call may be required.Depending on the contractual relationship between the customer and thecontractor, the contractor may schedule a service call to the building.

The monitoring system may provide specific information to a contractor,such as identifying information of the customer's components, includingmake and model numbers, as well as indications of the specific partnumbers of components. Based on this information, the contractor canallocate the correct repair personnel that have experience with thespecific components and/or the system. In addition, a service technicianis able to bring replacement parts, avoiding return trips afterdiagnosis.

Depending on the severity of the failure, the customer and/or contractormay be advised of relevant factors in determining whether to repair orreplace some or all of the components. For example only, these factorsmay include relative costs of repair versus replacement, and may includequantitative or qualitative information about advantages of replacementequipment. For example, expected increases in efficiency and/or comfortwith new equipment may be provided. Based on historical usage dataand/or electricity or other commodity prices, the comparison may alsoestimate annual savings resulting from the efficiency improvement.

As mentioned above, the monitoring system may also predict impendingfailures. This allows for preventative maintenance and repair prior toan actual failure of components. Alerts regarding detected or impendingfailures reduce the time when the HVAC system is out of operation andallows for more flexible scheduling for both the customer andcontractor. If the customer is out of town, these alerts may preventdamage from occurring when the customer is not present to detect thefailure of a component. For example, failure of heating components ofthe HVAC system in winter may lead to pipes freezing and bursting.

Alerts regarding potential or impending failures may specify statisticaltimeframes before the failure is expected. For example only, if a sensoris intermittently providing bad data, the monitoring system may specifyan expected amount of time before it is likely that the sensoreffectively stops working due to the prevalence of bad data. Further,the monitoring system may explain, in quantitative or qualitative terms,how the current operation and/or the potential failure will affectoperation of the HVAC system. This enables the customer to prioritizeand budget for repairs.

For the monitoring service, the monitoring company may charge a periodicrate, such as a monthly rate. This charge may be billed directly to thecustomer and/or may be billed to the contractor. The contractor may passalong these charges to the customer and/or may make other arrangements,such as by requiring an up-front payment and/or applying surcharges torepairs and service visits.

The monitoring service allows the customer to remotely monitor real-timedata within the building, outside of the building, and/or controlcomponents of the system, such as setting temperature and RH setpointsand other IAQ setpoints, enabling or disabling heating, cooling,ventilation, air purification, etc. In addition, the customer may beable to track usage data for components of the system and/or historicaldata.

In addition to being uploaded to the remote monitoring service (alsoreferred to as the cloud), monitored data may be transmitted to a localdevice in the building. For example, a smartphone, laptop, orproprietary portable device may receive monitoring information todiagnose problems and receive real-time performance data. Alternatively,data may be uploaded to the cloud and then downloaded onto a localcomputing device, such as via the Internet from an interactive web site.

In FIG. 1, a block diagram of an example HVAC system is presented. Inthis particular example, a forced air system with a gas furnace isshown. Return air is pulled from the building through a filter 104 by acirculator blower 108. The circulator blower 108, also referred to as afan, is controlled by a control module 112. The control module 112receives signals from a thermostat 116. For example only, the thermostat116 may include one or more temperature set points specified by theuser.

The thermostat 116 may direct that the circulator blower 108 be turnedon at all times or only when a heat request or cool request is present(automatic fan mode). In various implementations, the circulator blower108 can operate at one or more discrete speeds or at any speed within apredetermined range. For example, the control module 112 may switch oneor more switching relays (not shown) to control the circulator blower108 and/or to select a speed of the circulator blower 108.

The thermostat 116 provides the heat and/or cool requests to the controlmodule 112. When a heat request is made, the control module 112 causes aburner 120 to ignite. Heat from combustion is introduced to the returnair provided by the circulator blower 108 in a heat exchanger 124. Theheated air is supplied to the building and is referred to as supply air.

The burner 120 may include a pilot light, which is a small constantflame for igniting the primary flame in the burner 120. Alternatively,an intermittent pilot may be used in which a small flame is first litprior to igniting the primary flame in the burner 120. A sparker may beused for an intermittent pilot implementation or for direct burnerignition. Another ignition option includes a hot surface igniter, whichheats a surface to a high enough temperature that, when gas isintroduced, the heated surface initiates combustion of the gas. Fuel forcombustion, such as natural gas, may be provided by a gas valve 128.

The products of combustion are exhausted outside of the building, and aninducer blower 132 may be turned on prior to ignition of the burner 120.In a high efficiency furnace, the products of combustion may not be hotenough to have sufficient buoyancy to exhaust via conduction. Therefore,the inducer blower 132 creates a draft to exhaust the products ofcombustion. The inducer blower 132 may remain running while the burner120 is operating. In addition, the inducer blower 132 may continuerunning for a set period of time after the burner 120 turns off.

A single enclosure, which will be referred to as an air handler unit136, may include the filter 104, the circulator blower 108, the controlmodule 112, the burner 120, the heat exchanger 124, the inducer blower132, an expansion valve 140, an evaporator 144, and a condensate pan146. In various implementations, the air handler unit 136 includes anelectrical heating device (not shown) instead of or in addition to theburner 120. When used in addition to the burner 120, the electricalheating device may provide backup or secondary (extra) heat to theburner 120.

In FIG. 1, the HVAC system includes a split air conditioning system.Refrigerant is circulated through a compressor 148, a condenser 152, theexpansion valve 140, and the evaporator 144. The evaporator 144 isplaced in series with the supply air so that when cooling is desired,the evaporator 144 removes heat from the supply air, thereby cooling thesupply air. During cooling, the evaporator 144 is cold (e.g., below thedew point of the air within the building), which causes water vapor tocondense. This water vapor is collected in the condensate pan 146, whichdrains or is pumped out.

A control module 156 receives a cool request from the control module 112and controls the compressor 148 accordingly. The control module 156 alsocontrols a condenser fan 160, which increases heat exchange between thecondenser 152 and outside air. In such a split system, the compressor148, the condenser 152, the control module 156, and the condenser fan160 are generally located outside of the building, often in a singlecondensing unit 164.

In various implementations, the control module 156 may include a runcapacitor, a start capacitor, and a contactor or relay. In variousimplementations, the start capacitor may be omitted, such as when thecondensing unit 164 includes a scroll compressor instead of areciprocating compressor. The compressor 148 may be a variable-capacitycompressor and may respond to a multiple-level cool request. Forexample, the cool request may indicate a mid-capacity call for coolingor a high-capacity call for cooling. The compressor 148 may vary itscapacity according to the cool request.

The electrical lines provided to the condensing unit 164 may include a240 volt mains power line (not shown) and a 24 volt switched controlline. The 24 volt control line may correspond to the cool request shownin FIG. 1. The 24 volt control line controls operation of the contactor.When the control line indicates that the compressor should be on, thecontactor contacts close, connecting the 240 volt power supply to thecompressor 148. In addition, the contactor may connect the 240 voltpower supply to the condenser fan 160. In various implementations, suchas when the condensing unit 164 is located in the ground as part of ageothermal system, the condenser fan 160 may be omitted. When the 240volt mains power supply arrives in two legs, as is common in the U.S.,the contactor may have two sets of contacts, and can be referred to as adouble-pole single-throw switch.

Typically, the thermostat 116 includes a temperature sensor and arelative humidity (RH) sensor. When in a heating (heat) mode, thethermostat 116 generates a heat request when the temperature measured bythe temperature sensor is less than a lower temperature limit. When in acooling (cool) mode, the thermostat 116 generates a cool request whenthe temperature measured by the temperature sensor is greater than anupper temperature limit. The upper and lower temperature limits may beset to a setpoint temperature+ and − a predetermined amount (e.g., 1, 2,3, 4, 5 degrees Fahrenheit), respectively. The setpoint temperature maybe set to a predetermined temperature by default and may be adjusted bya user.

FIGS. 2A-2B are functional block diagrams of an example monitoringsystem associated with an HVAC system of a building. The air handlerunit 136 of FIG. 1 is shown for reference. The thermostat 116 of FIG. 1is a WiFi thermostat 208 having networking capability.

In many systems, the air handler unit 136 is located inside thebuilding, while the condensing unit 164 is located outside the building.The present disclosure is not limited to that arrangement, however, andapplies to other systems including, as examples only, systems where thecomponents of the air handler unit 136 and the condensing unit 164 arelocated in close proximity to each other or even in a single enclosure.The single enclosure may be located inside or outside of the building.In various implementations, the air handler unit 136 may be located in abasement, garage, or attic. In ground source systems, where heat isexchanged with the earth, the air handler unit 136 and the condensingunit 164 may be located near the earth, such as in a basement,crawlspace, garage, or on the first floor, such as when the first flooris separated from the earth by only a concrete slab.

In FIG. 2A, a transformer 212 can be connected to an AC line in order toprovide AC power to the control module 112 and the thermostat 208. Forexample, the transformer 212 may be a 10-to-1 transformer and thereforeprovide either a 12V or 24V AC supply depending on whether the airhandler unit 136 is operating on nominal 120 volt or nominal 240 voltpower.

The control module 112 controls operation in response to signals fromthe thermostat 208 received over control lines. The control lines mayinclude a call for cool (cool request), a call for heat (heat request),and a call for fan (fan request). The control lines may include a linecorresponding to a state of a reversing valve in heat pump systems.

The control lines may further carry calls for secondary heat and/orsecondary cooling, which may be activated when the primary heating orprimary cooling is insufficient. In dual fuel systems, such as systemsoperating from either electricity or natural gas, control signalsrelated to the selection of the fuel may be monitored. Further,additional status and error signals may be monitored, such as a defroststatus signal, which may be asserted when the compressor is shut off anda defrost heater operates to melt frost from an evaporator.

One or more of these control signals (on the control lines) is alsotransmitted to the condensing unit 164 (shown in FIGS. 2B and 2C). Invarious implementations, the condensing unit 164 may include an ambienttemperature sensor that generates temperature data. When the condensingunit 164 is located outdoors, the ambient temperature represents anoutside (or outdoor) ambient temperature. The temperature sensorsupplying the ambient temperature may be located outside of an enclosureof the condensing unit 164. Alternatively, the temperature sensor may belocated within the enclosure, but exposed to circulating air. In variousimplementations the temperature sensor may be shielded from directsunlight and may be exposed to an air cavity that is not directly heatedby sunlight. Alternatively or additionally, online (includingInternet-based) weather data based on the geographical location of thebuilding may be used to determine sun load, outside ambient airtemperature, relative humidity, particulate, VOCs, carbon dioxide, etc.

In FIG. 2C, an example condensing unit 268 is shown for a heat pumpimplementation. The condensing unit 268 may be configured similarly tothe condensing unit 164 of FIG. 2B. Although referred to as thecondensing unit 268, the mode of the heat pump determines whether thecondenser 152 of the condensing unit 268 is actually operating as acondenser or as an evaporator. A reversing valve 272 is controlled by acontrol module 276 and determines whether the compressor 148 dischargescompressed refrigerant toward the condenser 152 (cooling mode) or awayfrom the condenser 152 (heating mode). The control module 276 controlsthe reversing valve 272 and the compressor 148 based on the controlsignals. The control module 276 may receive power, for example, from thetransformer 212 of the air handler unit 136 or via the incoming AC powerline.

FIG. 3 includes a functional block diagram of an example indoor airquality (IAQ) sensor module 304 that can be used with an HVAC systemand/or one or more other mitigation devices. The IAQ sensor module 304includes one, more than one, or all of: a temperature sensor 308, arelative humidity (RH) sensor 312, a particulate sensor 316, a volatileorganic compounds (VOC) sensor 320, and a carbon dioxide sensor 324. TheIAQ sensor module 304 may also include a sampling module 328 and atransceiver module 332.

A power supply 336 may receive AC power from a standard wall outlet (orreceptacle) 340 via a plug 344. For example, the standard wall outlet340 may provide nominal 120 volt or nominal 240 volt AC power. The powersupply 336 may include an AC to direct current (DC) converter thatconverts the AC power into DC power, such as 5 volt, 12 volt, or 24 voltDC power. The power supply 336 supplies power to the components of theIAQ sensor module 304 including the sensors, the sampling module 328,and the transceiver module 332. While the example of the power supply336 being integrated within the IAQ sensor module 304 is provided, thepower supply 336 may be integrated with the plug 344 in variousimplementations. Also, while the example of the power supply 336providing one DC voltage to the components of the IAQ sensor module 304,the power supply 336 may provide two or more different DC voltages todifferent components of the IAQ sensor module 304.

Additionally or alternatively, the power supply 336 may include one ormore batteries or one or more solar cells that supply power to thecomponents of the IAQ sensor module 304. The one or more batteries maybe replaceable or non-replaceable. In the example of the one or morebatteries being non-replaceable, the one or more batteries may bere-chargeable, such as via a standard wall outlet. In this example, theIAQ sensor module 304 may include a charger that charges the one or morebatteries using power supplied, for example, via a standard wall outlet.

The IAQ sensor module 304 is portable and can be moved into differentrooms of a building. The IAQ sensor module 304 could also be placedoutside the building, for example, to measure one or more conditionsoutside of the building, calibration, or for one or more other reasons.The temperature sensor 308 measures a temperature of air at the IAQsensor module 304. The RH sensor 312 measures a relative humidity of airat the IAQ sensor module 304. The particulate sensor 316 measures anamount (e.g., a mass flow rate, such as micrograms (μg) per cubic meter)of particulate in air at the IAQ sensor module 304 having a diameterthat is less than a predetermined size (e.g., 2.5 or 10 micrometers(μm)). The VOC sensor 320 measures an amount (e.g., parts per billion(ppb)) of VOC in air at the IAQ sensor module 304. The carbon dioxidesensor 324 measures an amount (e.g., ppm) of carbon dioxide in air atthe IAQ sensor module 304. The included ones of the temperature sensor308, the RH sensor 312, the particulate sensor 316, the VOC sensor 320,and the carbon dioxide sensor 324 will be referred to collectively asthe IAQ sensors.

The sampling module 328 samples (analog) measurements of the IAQsensors. The sampling module 328 may also digitize and/or store valuesof the measurements of the IAQ sensors. In various implementations, theIAQ sensors may be digital sensors and output digital valuescorresponding to the respective measured parameters. In suchimplementations, the sampling module 328 may perform storage or may beomitted.

The IAQ sensor module 304 may include one or more expansion ports toallow for connection of additional sensors and/or to allow connection toother devices. Examples of other devices include one or more other IAQsensor modules, one or more other types of the IAQ sensors not includedin the IAQ sensor module 304, a home security system, a proprietaryhandheld device for use by contractors, a mobile computing device, andother types of devices.

The transceiver module 332 transmits frames of data corresponding topredetermined periods of time. Each frame of data may include themeasurements of the IAQ sensors over a predetermined period. One or morecalculations may be performed for the data of each frame of data, suchas averaging the measurements of one or more of the IAQ sensors. Eachframe (including the calculations and/or the measurements) may betransmitted to a monitoring system, as discussed further below. Themeasurements of the IAQ sensors may be sampled at a predetermined rate,such as 10 samples per minute or another suitable rate. Each frame maycorrespond to a predetermined number of sets of samples (e.g., 10). Themonitoring system may provide visual representations of the measurementsover predetermined periods of time along with other data, as discussedfurther below.

The transceiver module 332 transmits each frame (including thecalculations and/or the measurements) to an IAQ control module 404and/or the thermostat 208. The transceiver module 332 transmits theframes wirelessly via one or more antennas, such as antenna 348, using aproprietary or standardized, wired or wireless protocol, such asBluetooth, ZigBee (IEEE 802.15.4), 900 Megahertz, 2.4 Gigahertz, WiFi(IEEE 802.11). The IAQ sensor module 304 may communicate directly withthe IAQ control module 404 and/or the thermostat 208 or with a separatecomputing device, such as a smartphone, tablet, or another type ofcomputing device. In various implementations, a gateway 408 isimplemented, which creates a wireless network for the IAQ sensor module304, the IAQ control module 404, and the thermostat 208. The gateway 408may also interface with a customer router 412 using a wired or wirelessprotocol, such as Ethernet (IEEE 802.3).

Referring now to FIGS. 4A-4C, functional block diagrams of example IAQcontrol systems are presented. The IAQ control module 404 maycommunicate with the customer router 412 using WiFi. Alternatively, theIAQ control module 404 may communicate with the customer router 412 viathe gateway 408. The thermostat 208 may also communicate with thecustomer router 412 using WiFi or via the gateway 408. In variousimplementations, the IAQ control module 404 and the thermostat 208 maycommunicate directly or via the gateway 408.

The IAQ sensor module 304, the IAQ control module 404, and/or thethermostat 208 transmits data measured by the IAQ sensor module 304 andparameters of the IAQ control module 404 and/or the thermostat 208 overa wide area network 416, such as the Internet (referred to as theInternet 416). The IAQ sensor module 304, the IAQ control module 404,and/or the thermostat 208 may access the Internet 416 using the customerrouter 412 of the customer. The customer router 412 may already bepresent to provide Internet access to other devices (not shown) withinthe building, such as a customer computer and/or various other deviceshaving Internet connectivity, such as a DVR (digital video recorder) ora video gaming system.

The IAQ sensor module 304, the IAQ control module 404, and/or thethermostat 208 transmit the data to a remote monitoring system 420 viathe Internet 416 using the customer router 412. Further discussion ofthe remote monitoring system 420 is provided below.

The IAQ control module 404 and/or the thermostat 208 control operation(e.g., on, off, speed, etc.) of mitigation devices 424 based on themeasurements from the IAQ sensor module 304. For example, themeasurements of the IAQ sensor module 304 may be provided to thethermostat 208 and the thermostat 208 may control operation of themitigation devices 424 in various implementations (e.g., FIG. 4A). TheIAQ control module 404 can be omitted in such implementations. While theexample of the thermostat 208 controlling the mitigation devices 424will be discussed, alternatively the IAQ control module 404 may controloperation of the mitigation devices 424 (e.g., FIG. 4B), or thethermostat 208 and the IAQ control module 404 may together control themitigation devices 424 (e.g., FIG. 4C).

The IAQ control module 404 and/or thermostat 208 control and communicatewith the mitigation devices 424 wirelessly, by wire, using a combinationof wireless and wired connections. In the case of wireless control andcommunication, the IAQ control module 404, the thermostat 208, and themitigation devices 424 include respective transceivers.

The mitigation devices 424 include: (i) the condensing unit 164, (ii)the air handler unit 136 (e.g., the circulator blower 108), (iii) an aircleaner/purifier 428, (iv) a humidifier 432, (v) a dehumidifier 436, and(vi) a ventilator 440. The air cleaner/purifier 428 may be separate fromthe air handler unit 136 (e.g., a standalone air cleaner/purifier). Invarious implementations, the air handler unit 136 may serve as the aircleaner/purifier 428. The air cleaner/purifier 428 draws in air andforces the air through a filter before expelling filtered air to thebuilding. The filter may be rated (e.g., minimum efficiency reportingvalue, MERV) to remove a predetermined amount (e.g., 95%) of particulateof the size measured by the particulate sensor 316. Operation of the aircleaner/purifier 428 may include whether the air cleaner/purifier 428 ison or off and, when on, a speed of the air cleaner/purifier 428. The aircleaner/purifier 428 may have a single speed or multiple discretespeeds.

Operation of the air cleaner/purifier 428 may be controlled via wire orwirelessly by the thermostat 208. Examples of wireless communication andcontrol include, but are not limited to, Bluetooth connections and WiFiconnections. For example only, the thermostat 208 may wirelessly controlwhether the air cleaner/purifier 428 is on or off and, if on, the speedof the air cleaner/purifier 428. As one example, the thermostat 208 mayturn the air cleaner/purifier 428 on when the amount of particulatemeasured by the particulate sensor 316 is greater than a firstpredetermined amount of particulate. The thermostat 208 may leave theair cleaner/purifier 428 on until the amount of particulate measured bythe particulate sensor 316 is less than a second predetermined amount ofparticulate that is less than the first predetermined amount ofparticulate. The thermostat 208 may turn the air cleaner/purifier 428off when the amount of particulate measured by the particulate sensor316 is less than the second predetermined amount of particulate. Invarious implementations, the thermostat 208 may vary the speed of theair cleaner/purifier 428 based on the amount of particulate measured bythe particulate sensor 316. For example, the thermostat 208 may increasethe speed of the air cleaner/purifier 428 as the amount of particulateincreases and vice versa.

The humidifier 432 humidifies air within the building. The humidifier432 may be included with the air handler unit 136 or a standalonehumidifier. For example, when included with the air handler unit 136,the humidifier 432 may add moisture to the supply air before the supplyair is output from vents to the building. The humidifier 432 may addmoisture to air, for example, by supplying water to a medium (e.g., apad) and forcing air (e.g., supply air) through the hydrated medium.Alternatively, the humidifier 432 may spray water in the form of mistinto air (e.g., supply air). In the example of a standalone humidifier,the humidifier 432 may spray water in the form of mist into air.

Operation of the humidifier 432 may include whether the humidifier 432is on or off. In various implementations, operation of the humidifier432 may also include a humidification rate (e.g., an amount of watersupplied to the pad or into the air as mist). The humidifier 432 may beconfigured to provide only a single humidification rate or multipledifferent humidification rates.

Operation of the humidifier 432 may be controlled via wire or wirelesslyby the thermostat 208. For example only, the thermostat 208 may control(by wire) whether the humidifier 432 included with the air handler unit136 is on or off. As another example, if the humidifier 432 isimplemented separately from the air handler unit 136, the thermostat 208may wirelessly control whether the humidifier 432 is on or off and ahumidification rate when on. Examples of wireless communication include,but are not limited to, Bluetooth connections and WiFi connections. Forexample only, the thermostat 208 may turn the humidifier 432 on when theRH measured by the RH sensor 312 is less than a first predetermined RH.The thermostat 208 may leave the humidifier 432 on until the RH measuredby the RH sensor 312 is greater than a second predetermined RH that isgreater than the first predetermined RH. The thermostat 208 may turn thehumidifier 432 off when the RH measured by the RH sensor 312 is greaterthan the second predetermined RH.

The dehumidifier 436 dehumidifies (i.e., removes humidity from) airwithin the building. The dehumidifier 436 may be included with the airhandler unit 136 or a standalone dehumidifier. For example, thedehumidifier 436 may draw moisture from the supply air (or add dry airto the supply air) before the supply air is output from vents to thebuilding. Operation of the dehumidifier 436 may include whether thedehumidifier 436 is on or off.

Operation of the dehumidifier 436 may be controlled via wire orwirelessly by the thermostat 208. For example only, the thermostat 208may control (by wire) whether the dehumidifier 436 included with the airhandler unit 136 is on or off. As another example, the thermostat 208may wirelessly control whether the dehumidifier 436, implemented as astandalone device, is on or off. For example only, the thermostat 208may turn the dehumidifier 436 on when the RH measured by the RH sensor312 is greater than a third predetermined RH. The third predetermined RHmay be the same as the second predetermined RH or different than (e.g.,greater than) the second predetermined RH. The thermostat 208 may leavethe dehumidifier 436 on until the RH measured by the RH sensor 312 isless than a fourth predetermined RH that is less than the thirdpredetermined RH. The thermostat 208 may turn the dehumidifier 436 offwhen the RH measured by the RH sensor 312 is less than the fourthpredetermined RH. The fourth predetermined RH may be the same as thefirst predetermined RH or different than (e.g., greater than) the firstpredetermined RH.

The ventilator 440 vents air from within the building out of thebuilding. This also passively draws air from outside of the buildinginto the building. The ventilator 440 may be included with the airhandler unit 136 (e.g., the inducer blower 132) or a standaloneventilator. Examples of standalone ventilators include blowers that blowair from within the building out of the building (e.g., range hoodsfans, bathroom fans, the inducer blower, etc.). Operation of theventilator 440 may include whether the ventilator 440 is on or off and,when on, a speed. The ventilator 440 may be configured to operate at asingle speed or multiple different speeds.

Operation of the ventilator 440 may be controlled via wire or wirelesslyby the thermostat 208. For example only, the thermostat 208 maywirelessly control whether the ventilator 440 is on or off and, if on,the speed of the ventilator 440. As one example, the thermostat 208 mayturn the ventilator 440 on when the amount of VOCs measured by the VOCsensor 320 is greater than a first predetermined amount of VOCs. Thethermostat 208 may leave the ventilator 440 on until the amount of VOCsmeasured by the VOC sensor 320 is less than a second predeterminedamount of VOCs that is less than the first predetermined amount of VOCs.The thermostat 208 may turn the ventilator 440 off when the amount ofVOCs measured by the VOC sensor 320 is less than the secondpredetermined amount of VOCs.

As another example, the thermostat 208 may turn the ventilator 440 onwhen the amount of carbon dioxide measured by the carbon dioxide sensor324 is greater than a first predetermined amount of carbon dioxide. Thethermostat 208 may leave the ventilator 440 on until the amount ofcarbon dioxide measured by the carbon dioxide sensor 324 is less than asecond predetermined amount of carbon dioxide that is less than thefirst predetermined amount of carbon dioxide. The thermostat 208 mayturn the ventilator 440 off when the amount of carbon dioxide measuredby the carbon dioxide sensor 324 is less than the second predeterminedamount of carbon dioxide.

The mitigation devices described above are only described as example.One or more of the example mitigation devices may be omitted. One ormore other types of mitigation devices may be included. Additionally,while the example of only one of each type of mitigation device isprovided, two or more of a given type of mitigation device may beincluded and controlled.

Changes in temperature and/or humidity also cause changes inparticulate, VOCs, and/or carbon dioxide. For example, a change intemperature may cause a change in VOCs, RH, particulate, and/or carbondioxide. As another example, a change in RH may cause a change inparticulate, VOCs, and/or carbon dioxide. For example, particulate mayincrease as RH increases and vice versa.

The thermostat 208 therefore controls operation of the mitigationdevices 424 based on all of the parameters measured by the IAQ sensormodule 304 in an attempt to: adjust the temperature within apredetermined temperature range, adjust the RH within a predetermined RHrange, adjust the amount of particulate (if measured) to less than apredetermined amount of particulate, adjust the amount of VOCs (ifmeasured) to less than a predetermined amount of VOCs, and to adjust theamount of carbon dioxide (if measured) to less than a predeterminedamount of carbon dioxide.

FIG. 5A includes a functional block diagram of an example monitoringsystem. In FIG. 5A, the IAQ control module 404 and/or the thermostat 208are shown transmitting, using the customer router 412, data to theremote monitoring system 420 via the Internet 416. In otherimplementations, the IAQ control module 404 and/or the thermostat 208may transmit the data to an external wireless receiver. The externalwireless receiver may be a proprietary receiver for a neighborhood inwhich the building is located, or may be an infrastructure receiver,such as a metropolitan area network (such as WiMAX), a WiFi accesspoint, or a mobile phone base station.

The remote monitoring system 420 includes a monitoring server 508 thatreceives data from the IAQ control module 404 and/or the thermostat 208and maintains and verifies network continuity with the IAQ controlmodule 404 and/or the thermostat 208. The monitoring server 508 executesvarious algorithms to store setpoints for the building and to storemeasurements from the thermostat 208 and/or the IAQ sensor module 304taken over time.

The monitoring server 508 may notify a review server 512 when one ormore predetermined conditions are satisfied. This programmaticassessment may be referred to as an advisory. Some or all advisories maybe triaged by a technician to reduce false positives and potentiallysupplement or modify data corresponding to the advisory. For example, atechnician device 516 operated by a technician may be used to review theadvisory and to monitor data (in various implementations, in real-time)from the IAQ control module 404 and/or the thermostat 208 via themonitoring server 508.

A technician using the technician device 516 may review the advisory. Ifthe technician determines that a problem or fault is either alreadypresent or impending, the technician instructs the review server 512 tosend an alert to a customer device 524 that is associated with thebuilding. The technician may determine that, although a problem or faultis present, the cause is more likely to be something different thanspecified by the automated advisory. The technician can therefore issuea different alert or modify the advisory before issuing an alert basedon the advisory. The technician may also annotate the alert sent to thecustomer device 524 with additional information that may be helpful inidentifying the urgency of addressing the alert and presenting data thatmay be useful for diagnosis or troubleshooting.

In various implementations, minor problems may not be reported to thecustomer device 524 so as not to alarm the customer or inundate thecustomer with alerts. The review server 512 (or a technician) maydetermine whether a problem is minor based on a threshold. For example,an efficiency decrease greater than a predetermined threshold may bereported to the customer device 524, while an efficiency decrease lessthan the predetermined threshold may not be reported to the customerdevice 524.

In various implementations, the technician device 516 may be remote fromthe remote monitoring system 420 but connected via a wide area network.For example only, the technician device 516 may include a computingdevice such as a laptop, desktop, smartphone, or tablet.

Using the customer device 524 executing an application, the customer canaccess a customer portal 528, which provides historical and real-timedata from the IAQ control module 404 and/or the thermostat 208. Thecustomer portal 528 may also provide setpoints and predetermined rangesfor each of the measurements, local outdoor air quality data, statusesof the mitigation devices 424 (e.g., on or off), and other data to thecustomer device 524. Via the customer device 524, the customer maychange the setpoints and predetermined ranges. The monitoring server 508transmits changed setpoints and predetermined ranges to the thermostat208 and/or the IAQ control module 404 for use in controlling operationof the mitigation devices 424.

The remote monitoring system 420 includes a local data server 520 thatobtains local data at (outside) the building. The local data server 520may obtain the local data from one or more local data sources 532 via awide area network, such as the internet 416, using a geographicallocation of the building. The geographical location may be, for example,an address, zip code, coordinates, or other geographical identifier ofthe building. The remote monitoring system 420 may obtain thegeographical location of the building, for example, via the customerdevice 524 before providing data to the customer device 524. The localdata includes, for example, air temperature within a predeterminedgeographical area including the geographical location of the building,RH within the predetermined geographical area, amount of VOCs in the airwithin the predetermined geographical area, amount of particulate of thepredetermined size measured by the particulate sensor 316 within thepredetermined geographical area, and amount of carbon dioxide within thepredetermined geographical area.

FIG. 5B includes a functional block diagram of an example monitoringsystem where the customer device 524 serves as a monitoring system andprovides the functionality of the remote monitoring system 420. Thethermostat 208 and/or the IAQ control module 404 transmit data to thecustomer device 524 wirelessly, such as via a Bluetooth connection,WiFi, or another wireless connection. The customer device 524 may obtainthe local data from the local data sources 532 via a wide area network,such as the internet 416. Alternatively, the IAQ control module 404 orthe thermostat 208 may serve as a monitoring system and provide thefunctionality of the remote monitoring system 420.

FIG. 6 includes an example user interface displayed by the customerdevice 524 during execution of the application based on data from thecustomer portal 528. It should be understood that the followingfunctions are performed by the customer device 524 during execution ofthe application.

As shown in FIG. 6, the customer device 524 may display real-time valuesof the temperature, RH, amount of VOCs, amount of particulate, andamount of carbon dioxide (CO2) measured by the IAQ sensor module 304. InFIG. 6, these are illustrated in the row labeled “indoor” as theyrepresent parameters within the building. The real-time values may bereceived by the customer device 524 from the monitoring server 508 viathe customer portal 528.

The customer device 524 may also display real-time values of thetemperature, RH, amount of VOCs, amount of particulate, and amount ofcarbon dioxide (CO2) measured outside of the building but within thepredetermined geographical area including the geographical area of thebuilding. In FIG. 6, these are illustrated in the row labeled “outdoor”as they represent parameters outside of the building. The real-timevalues may be received by the customer device 524 from the monitoringserver 508 via the customer portal 528.

The customer device 524 may also display present setpoints for beginningheating (Heat) of the building, cooling (Cool) of the building,humidification (Humidify), dehumidification (Dehumidify), VOC removal(VOCs), particulate removal (Particulate), and carbon dioxide removal(Carbon Dioxide). In FIG. 6, these setpoints are illustrated in the rowlabeled “setpoints” as they represent setpoints for beginning associatedmitigation actions within the building. The present setpoints may bereceived by the customer device 524 from the monitoring server 508 viathe customer portal 528.

A predetermined range for a measurement may be set based on the setpointfor a measurement. For example, a predetermined range for heating may beset to the temperature setpoint for heating plus and minus apredetermined amount. A predetermined range for cooling may be set tothe temperature setpoint for cooling plus and minus a predeterminedamount. The predetermined amount may be user adjustable in variousimplementations.

The customer device 524 also allows a user to adjust one or more of thepresent setpoints via the customer device 524. For example, the customerdevice 524 may provide positive and negative adjustment inputs inassociation with one, more than one, or all of the setpoints to allowfor adjustment of the present setpoints. FIG. 6 includes the example of+serving as the positive adjustment input and—serving as the negativeadjustment input. Adjustment inputs labeled and provided differently,however, may be used.

In response to receipt of input indicative of user interaction (e.g.,touching, clicking, etc.) with an adjustment input associated with asetpoint, the customer device 524 may transmit a command to themonitoring server 508 to adjust (i.e., increment or decrement) thesetpoint by a predetermined amount. For example, in response to receiptof input indicative of user interaction (e.g., touching, clicking, etc.)with the positive adjustment input associated with the heatingtemperature setpoint, the customer device 524 may transmit a command tothe monitoring server 508 to increment the heating temperature setpointby a first predetermined amount. In response to receipt of inputindicative of user interaction (e.g., touching, clicking, etc.) with thenegative adjustment input associated with the heating temperaturesetpoint, the customer device 524 may transmit a command to themonitoring server 508 to decrement the heating temperature setpoint bythe first predetermined amount. As another example, in response toreceipt of input indicative of user interaction (e.g., touching,clicking, etc.) with the positive adjustment input associated with thehumidification RH setpoint, the customer device 524 may transmit acommand to the monitoring server 508 to increment the humidification RHsetpoint by a second predetermined amount. In response to receipt ofinput indicative of user interaction (e.g., touching, clicking, etc.)with the negative adjustment input associated with the humidification RHsetpoint, the customer device 524 may transmit a command to themonitoring server 508 to decrement the humidification RH setpoint by thesecond predetermined amount.

The monitoring server 508 relays (transmits) received commands foradjusting setpoints to the thermostat 208 and/or the IAQ control module404 via the internet 416. Alternatively, the customer device 524 maytransmit commands for adjusting setpoints to the thermostat 208 and/orthe IAQ control module 404 directly or via the internet 416. Thethermostat 208 and/or the IAQ control module 404 adjust the associatedsetpoints in response to the commands received from the monitoringserver 508.

As discussed above, one or more than one IAQ sensor module 304 may beconcurrently used within the building, such as in different rooms of thebuilding. FIG. 7 includes an example user interface displayed by thecustomer device 524 during execution of the application when thebuilding includes multiple IAQ sensor modules. In the example of FIG. 7,the measurements from each IAQ sensor module are shown in a separatecolumn.

As also discussed above, one or more of the IAQ sensors may be omittedfrom an IAQ sensor module. For example, as shown in the right-mostcolumn of FIG. 7, the associated IAQ sensor module only includes aparticulate sensor and a carbon dioxide sensor. The temperature,relative humidity, and VOCs of zero in the example of FIG. 7 indicatethat the IAQ sensor module does not include a temperature sensor, ahumidity sensor, or a VOC sensor.

FIG. 8 includes an example user interface displayed by the customerdevice 524 during execution of the application based on additional dataindicative of present statuses of control modes and present (operation)statuses of various devices and modes of devices of the building. Thepresent statuses may be, for example, on or off. The present status of acontrol mode, device, or mode of a device may be on (currently in use)or off (not currently in use). One type of indicator may be used toindicate a present status of on, while another type of indicator may beused to indicate a present status of off. The customer device 524 maydisplay the additional data concurrently with the data from one or moreIAQ modules, the local data, and/or the setpoint data.

The customer device 524 selectively displays measurements of one or moreIAQ sensor modules, local data, control modes, and/or statuses from apredetermined period of time. The predetermined period of time may be,for example, the present day, a predetermined number of days (includingor not including the present day), a predetermined number of hoursbefore a present time, a predetermined number of minutes before thepresent time, or another suitable period. By default, a predeterminedperiod may be selected (e.g., the present day), but a user may select adifferent predetermined period and the customer device 524 may displaythe data for the selected predetermined period.

FIG. 9 includes an example user interface displayed by the customerdevice 524 during execution of the application for the present day (from12:01 pm of the present day to the present time (approximately 10 pm inthis example)). The customer device 524 displays data selected by a userof the customer device 524. By default, all data may be selected, but auser may select less than all of the data to be displayed, and thecustomer device 524 may display only the selected data.

For example, in FIG. 9, only outdoor temperature (from the local data),outdoor RH (from the local data), indoor temperature (from the IAQsensor module 304), indoor RH (from the IAQ sensor module 304), andparticulate (from the IAQ sensor module 304) are graphed over time.Indicators of the statuses of the cooling mode, the heating mode, anduse of the circulator blower 108 are also concurrently shown over time.Indoor Carbon dioxide (from the IAQ sensor module 304, if measured) andindoor VOCs (from the IAQ sensor module 304, if measures) are notgraphed over time in this example.

The customer device 524 selectively displays a user interface for userselection of a priority for mitigating deviations in IAQ parameters(temperature, RH, particulate, VOCs, carbon dioxide). For example, thecustomer device 524 may display a user interface that allows userassignment of an order of prioritization for: (i) temperature control:(ii) RH control; (iii) particulate control; (vi) VOC control; and (v)carbon dioxide control. Temperature control may refer to maintaining, asmuch as possible, the temperature within the building within apredetermined temperature range. RH control may refer to maintaining, asmuch as possible, the RH within the building within a predeterminedtemperature range. Particulate control may refer to maintaining, as muchas possible, the amount of particulate within the building less than apredetermined amount of particulate. VOC control may refer tomaintaining, as much as possible, the amount of VOCs within the buildingless than a predetermined amount of VOCs. Carbon dioxide control mayrefer to maintaining, as much as possible, the amount of carbon dioxidewithin the building less than a predetermined amount of carbon dioxide.The order of prioritization for (i)-(v) may be initially preset, but maybe user selected, as stated above.

The thermostat 208 and/or the IAQ control module 404 may control themitigation devices 424 based on the prioritization (order). For example,when particulate control is the first priority, the thermostat 208 maycontrol the mitigation devices 424 to decrease particulate as quickly aspossible as opposed to, for example, controlling the mitigation devices424 to more quickly adjust temperature or RH or to more quickly decreasethe amount of VOCs and/or the amount of carbon dioxide.

The user interfaces provided by the customer device 524 provide visualinformation to the user regarding real-time measurements, historicalmeasurements over a period of time, trends, and efficacy of IAQmitigation and control. The user interfaces also enable the user toadjust setpoints to be used to control the mitigation devices 424 tocontrol comfort and IAQ within the building. The user interfaces alsoenable the user to adjust prioritization in which IAQ conditions aremitigated. All of the above improves IAQ within the building and userexperience regarding IAQ within the building.

FIG. 10 includes a block diagram of an example implementation of amitigation system using the example of the IAQ control module 404. Whilethe example of the IAQ control module 404 is provided for purposes ofdiscussion, the modules of the IAQ control module 404 may alternativelybe implemented within the thermostat 208 or within a combination of thethermostat 208 and the IAQ control module 404.

A mitigation module 1004 selectively turns on and off ones of themitigation devices 424 based on the associated ones of the IAQparameters and respective thresholds. A thresholds module 1008 sets thethresholds, as discussed further below. For example, the mitigationmodule 1004 may turn one or more filtering devices (e.g., the aircleaner/purifier 428 and/or the circulator blower 108) on when theamount of particulate measured by the particulate sensor 316 is greaterthan a first ON threshold amount of particulate and a second ONthreshold amount of particulate, such as described in FIGS. 11 to 13.The mitigation module 1004 may leave the one or more filtering deviceson until the amount of particulate measured by the particulate sensor316 becomes less than an OFF threshold amount of particulate and one ormore OFF conditions are satisfied. The mitigation module 1004 may turnthe one or more filtering devices off when the amount of particulatemeasured by the particulate sensor 316 is less than the OFF thresholdamount of particulate and one or more OFF conditions are satisfied.

The mitigation module 1004 may turn the ventilator 440 on when theamount of VOCs measured by the VOC sensor 320 is greater than a first ONVOC threshold and a second ON VOC threshold. The mitigation module 1004may leave the ventilator 440 on until the amount of VOCs measured by theVOC sensor 320 is less than an OFF VOC threshold and one or more OFFconditions are satisfied. The mitigation module 1004 may turn theventilator 440 off when the amount of VOCs measured by the VOC sensor320 is less than the OFF VOC threshold and one or more OFF conditionsare satisfied.

The mitigation module 1004 may turn the ventilator 440 on when theamount of carbon dioxide measured by the carbon dioxide sensor 324 isgreater than a first ON carbon dioxide threshold and a second ON carbondioxide threshold. The mitigation module 1004 may leave the ventilator440 on until the amount of carbon dioxide measured by the carbon dioxidesensor 324 is less than an OFF carbon dioxide threshold. The mitigationmodule 1004 may turn the ventilator 440 off when the amount of carbondioxide measured by the carbon dioxide sensor 324 is less than the OFFcarbon dioxide threshold.

The thresholds module 1008 sets the first ON threshold amount ofparticulate, the second ON threshold amount of particulate, and the OFFthreshold amount of particulate. The thresholds module 1008 also setsthe first ON VOC threshold, the second ON VOC threshold, and the OFF VOCthreshold. The thresholds module 1008 also sets the first ON carbondioxide threshold, the second ON carbon dioxide threshold, and the OFFcarbon dioxide threshold.

The thresholds module 1008 sets the first ON threshold amount ofparticulate based on a clean amount of particulate in the air and an ONpredetermined amount of particulate. For example, the thresholds module1008 may set the first ON threshold amount of particulate to the cleanamount of particulate plus the ON predetermined amount of particulate.The ON predetermined amount of particulate may be a fixed predeterminedvalue or may be a variable, such as a percentage (less than 100 percent)or a fraction (less than 1) of the clean amount of particulate. This mayensure that there is no nuisance due to sensor response errorvariability.

The thresholds module 1008 sets the second ON threshold amount ofparticulate to a fixed predetermined amount of particulate. The fixedpredetermined amount of particulate may be greater than, less than, orequal to the clean amount of particulate.

The thresholds module 1008 sets the OFF threshold amount of particulatebased on (a) an OFF predetermined amount of particulate and (b) thegreater one of the first ON threshold amount of particulate and thesecond ON threshold amount of particulate. For example, the thresholdsmodule 1008 may set the OFF threshold amount of particulate to (a) theOFF predetermined amount of particulate plus (b) the greater one of thefirst ON threshold amount of particulate and the second ON thresholdamount of particulate. The OFF predetermined amount of particulate maybe a fixed predetermined value or may be a variable, such as apercentage (less than 100 percent) or a fraction (less than 1) of theclean amount of particulate. The OFF threshold amount of particulatewill therefore be greater than both of the first and second ON thresholdamounts of particulate.

The thresholds module 1008 sets the first ON VOC threshold based on aclean amount of VOCs in the air and an ON predetermined amount of VOCs.For example, the thresholds module 1008 may set the first ON VOCthreshold to the clean amount of VOCs plus the ON predetermined amountof VOCs. The ON predetermined amount of VOCs may be a fixedpredetermined value or may be a variable, such as a percentage (lessthan 100 percent) or a fraction (less than 1) of the clean amount ofVOCs.

The thresholds module 1008 sets the second ON VOC threshold amount ofparticulate to a fixed predetermined amount of VOCs. The fixedpredetermined amount of VOCs may be greater than, less than, or equal tothe clean amount of VOCs.

The thresholds module 1008 sets the OFF VOC threshold based on (a) anOFF predetermined amount of VOCs and (b) the greater one of the first ONVOC threshold and the second ON VOC threshold. For example, thethresholds module 1008 may set the OFF VOC threshold amount to (a) theOFF predetermined amount of VOCs plus (b) the greater one of the firstON VOC threshold and the second ON VOC threshold. The OFF predeterminedamount of VOCs may be a fixed predetermined value or may be a variable,such as a percentage (less than 100 percent) or a fraction (less than 1)of the clean amount of VOCs. The OFF VOC threshold will therefore begreater than both of the first and second ON VOC thresholds.

The thresholds module 1008 sets the first ON carbon dioxide thresholdbased on a clean amount of carbon dioxide in the air and an ONpredetermined amount of carbon dioxide. For example, the thresholdsmodule 1008 may set the first ON carbon dioxide threshold to the cleanamount of carbon dioxide plus the ON predetermined amount of carbondioxide. The ON predetermined amount of carbon dioxide may be a fixedpredetermined value or may be a variable, such as a percentage (lessthan 100 percent) or a fraction (less than 1) of the clean amount ofcarbon dioxide.

The thresholds module 1008 sets the second ON carbon dioxide thresholdamount of particulate to a fixed predetermined amount of carbon dioxide.The fixed predetermined amount of carbon dioxide may be greater than,less than, or equal to the clean amount of carbon dioxide.

The thresholds module 1008 sets the OFF carbon dioxide threshold basedon (a) an OFF predetermined amount of carbon dioxide and (b) the greaterone of the first ON carbon dioxide threshold and the second ON carbondioxide threshold. For example, the thresholds module 1008 may set theOFF carbon dioxide threshold amount to (a) the OFF predetermined amountof carbon dioxide plus (b) the greater one of the first ON carbondioxide threshold and the second ON carbon dioxide threshold. The OFFpredetermined amount of carbon dioxide may be a fixed predeterminedvalue or may be a variable, such as a percentage (less than 100 percent)or a fraction (less than 1) of the clean amount of carbon dioxide. TheOFF carbon dioxide threshold will therefore be greater than both of thefirst and second ON carbon dioxide thresholds.

A clean module 1012 sets the clean amount of particulate, the cleanamount of VOCs, and the clean amount of carbon dioxide. The cleanamounts can be derived for a given building as the average from thelowest amounts of particulate after the mitigation ON cycles. Thiscalculation may be performed during the first week after initialinstallation and updated daily, weekly, monthly, annually, or as needed.

The clean module 1012 monitors the date and time, the IAQ parameters,and the mitigation statuses. The clean module 1012 sets the clean amountof particulate based on or equal to an average of all of the amounts ofparticulate measured while particulate mitigation was OFF (i.e., thefiltering device(s) were OFF) during a last predetermined period, suchas the last 24 hours. Measurements of the amount of particulate takenwhile particulate mitigation was ON (one or more of the filteringdevice(s) were ON) are not considered in the determination of the cleanamount of particulate. The clean amount of particulate represents aminimum amount of particulate that the equipment of the building iscapable of achieving.

The clean module 1012 sets the clean amount of VOCs based on or equal toan average of all of the amounts of VOCs measured while VOC mitigationwas OFF (i.e., the ventilator 440 was OFF) during a last predeterminedperiod, such as the last 24 hours. Measurements of the amount of VOCstaken while VOC mitigation was ON (the ventilator 440 was ON) are notconsidered in the determination of the clean amount of VOCs. The cleanamount of particulate represents a minimum amount of VOCs that theequipment of the building is capable of achieving.

The clean module 1012 sets the clean amount of carbon dioxide based onor equal to an average of all of the amounts of carbon dioxide measuredwhile carbon dioxide mitigation was OFF (i.e., the ventilator 440 wasOFF) during a last predetermined period, such as the last 24 hours.Measurements of the amount of carbon dioxide taken while carbon dioxidemitigation was ON (the ventilator 440 was ON) are not considered in thedetermination of the clean amount of carbon dioxide. The clean amount ofparticulate represents a minimum amount of carbon dioxide that theequipment of the building is capable of achieving.

FIG. 11 includes an example graph of an IAQ parameter (e.g., amount ofparticulate, amount of VOCs, or amount of carbon dioxide) over time. Inthe example of FIG. 11, the clean amount of that IAQ parameter is lessthan the first ON threshold for that parameter, and the first ONthreshold for that parameter is less than the second ON threshold forthat parameter.

FIG. 12 includes an example graph of an IAQ parameter (e.g., amount ofparticulate, amount of VOCs, or amount of carbon dioxide) over time. Inthe example of FIG. 12, the clean amount of that IAQ parameter is lessthan the second ON threshold for that parameter, and the second ONthreshold for that parameter is less than the first ON threshold forthat parameter.

FIG. 13 includes an example graph of an IAQ parameter (e.g., amount ofparticulate, amount of VOCs, or amount of carbon dioxide) over time. Inthe example of FIG. 13, the second ON threshold for that parameter isless than the clean amount for that IAQ parameter, and the clean amountfor that IAQ parameter is less than the first ON threshold for thatparameter.

The use of both of the first and second ON thresholds may avoid nuisancemitigation cycles, for example, where the home is located in anenvironment where the outdoor pollutant levels are directly impactingthe clean level in the home. In this example, the clean level may beclose to or greater than second ON threshold (as depicted in FIGS. 12and 13), and the clean level may vary during the year, such as byseason. The use of both of the first and second ON thresholds may avoidnuisance mitigation cycles, for example, when sensor variability maycause a higher than normal measurement.

In the examples of FIGS. 11-13, the mitigation module 1004 turnsmitigation of that IAQ parameter ON at time X, when the IAQ parameter isgreater than both of the first and second ON thresholds. Y representsthe OFF threshold for the parameter. 1, 2, and 3 are potential timeswhen ones of the OFF conditions are satisfied and mitigation module 1004turns mitigation of that IAQ parameter OFF.

The OFF conditions include: the IAQ parameter being less than or equalto the clean amount of that IAQ parameter; the slope of the IAQparameter becoming greater than a predetermined negative value andapproaching zero (e.g., within a predetermined amount of zero); and thepassing of a (time) period after the IAQ parameter becomes less than theOFF threshold. The period may be a predetermined fixed period (e.g., 1hour) or a period determined, such as based on a time to capacity of themitigation device(s).

In FIGS. 11-13, time 1 corresponds to when the IAQ parameter is lessthan or equal to the clean amount of that IAQ parameter. Time 2corresponds to when the slope of the IAQ parameter is greater than thepredetermined negative value and approaching zero. Time 3 corresponds towhen the period has passed after the IAQ parameter is less than the OFFthreshold.

Use of the OFF conditions may ensure that the IAQ parameters are broughtdown close to clean amounts, respectively. This therefore provides amore effective control and mitigation strategy than simply using a hardOFF threshold for turning OFF mitigation. Additionally, this ensuresthat mitigation is not performed for an excessive amount of time.

In various implementations, a time to capacity module 1016 may determinethe period, based on an initial value of the IAQ parameter, a latervalue of the IAQ parameter, and characteristics of the building and themitigation device(s). For example, for particulate matter mitigation,the time to capacity module 1016 may set the period by solving thefollowing equation for the period:

${\left( {{Later}\mspace{14mu}{{PM}/{Initial}}\mspace{14mu}{PM}} \right) = \left( {1 - {\frac{afm}{vol}*{efficiency}}} \right)^{period}},$where period is the period, later PM is the later amount of particulate,initial PM is the initial amount of PM, afr is an air flow rate (e.g.,in cubic feet per minute (CFM)) of filtering device(s), vol is aninternal volume (e.g., in cubic feet) of the building, and efficiency isan efficiency (e.g., particulate filtering percentage) of a filter ofthe filtering device(s). In the example of turning off, the Initial PMmay be equal to the peak amount of particulate that occurred at orshortly after the filtering device(s) were turned on, and the Later PMmay be the clean amount of particulate.

FIG. 19 includes an example graph of amount of particulate over time(measured mitigation period) during mitigation events. Dashed traces1904 and 1908 track actual amounts of particulate measured using aparticulate sensor during mitigation events with MERV 8 and MERV 14rated filters. Solid traces 1912 and 1916 track amounts of particulateestimated using the equation above (solving for Later PM) duringmitigation events with MERV 8 and MERV 14 rated filters. As shown, theestimated amounts closely track the actual amounts over time fordifferent types of filters.

For carbon dioxide or VOC mitigation, the time to capacity module 1016may set the period by solving the following equation for the period:

${\left( {{Later}/{Initial}} \right) = \left( {1 - {\frac{afr}{vol}*{percentage}}} \right)^{period}},$where period is the period, Later is the later amount of VOC or carbondioxide, Initial is the initial amount of VOC or carbon dioxide, afr isan air flow rate (e.g., in CFM) of the fresh air ventilator 440 (e.g.,one or more bath fans), vol is the internal volume (e.g., in cubic feet)of the building, and percentage is the percentage of the volume of thebuilding that the ventilator 440 will circulate out of the building perminute (e.g., 160 cfm/16000 cubic foot building=1 percent). Thepercentage may be a fixed value or may be a variable based on whichventilator(s) are on and whether one or more other mitigation devicesare on. For example, the percentage may be multiplied by 1.5 if thecirculator blower 108 is also on simultaneously with the fresh airventilator(s). In the example of turning off, Initial may be equal tothe peak VOC value or the peak carbon dioxide value that occurredshortly at or shortly after the ventilator(s) was(were) turned on, andLater may be the clean VOC amount or the clean carbon dioxide amount.

FIG. 20 includes an example graph of amount of VOCs over time (measuredmitigation period) during a mitigation event. Dashed trace 2004 tracksactual amounts of VOCs measured using a VOC sensor during mitigationevents with both a bath fan (BF) and a circulator blower (WH) of an airhandler unit ON. Solid trace 2008 tracks amounts of VOCs estimated usingthe equation above (solving for Later) during mitigation events withboth the bath fan (BF) and the circulator blower (WH) of the air handlerunit ON. As shown, the estimated amounts closely track the actualamounts over time.

In various implementations, the period may be determined differently andbe used for other reasons. For example, the period may be compared witha measured value of the period to identify a fault, such as a dirtyfilter, or impending filter life. As another example, the period may beused to classify a mitigation event as a type of mitigation event and aseverity.

An example of a failure and impending failure of a mitigation deviceincludes a replacement of the filter 104. Over time, the filter 104 willfill with particulate from the air passing through the filter 104. Theequation above could be solved for the period to determine an expectedperiod for the filter 104 to mitigate particulate when the filter 104 isnew (initial installation or filter replacement). For example, forparticulate matter mitigation, the time to capacity module 1016 may setthe period by solving the following equation for the period:

${\left( {{Later}\mspace{14mu}{{PM}/{Initial}}\mspace{14mu}{PM}} \right) = \left( {1 - {\frac{afr}{vol}*{efficiency}}} \right)^{period}},$where period is the period, Later PM is the later amount of particulate,Initial PM is the initial amount of PM, afr is an air flow rate (e.g.,in CFM) of the filter 104, vol is the internal volume (e.g., in cubicfeet) of the building, and efficiency is an efficiency (e.g.,particulate filtering percentage) of the filter 104 when new. In thisexample, the Initial PM may be equal to the amount of particulate at thetime when the circulator blower 108 is turned on to decrease the amountof particulate in the air, and the Later PM may be the clean amount ofparticulate. The period would therefore reflect the expected period forthe filter 104, when new, to mitigate particulate to the clean level.

When the circulator blower 108 is turned on to decrease (mitigate) theamount of particulate in the air, a timer module 1020 may reset andstart a measured mitigation period. The timer module 1020 may increasethe measured mitigation period as time passes while the circulatorblower 108 is on.

When the mitigation module 1004 turns off the air handler unit 136circulator blower 108 to stop decreasing the amount of particulate inthe air, the measured mitigation period reflects the period that thecirculator blower 108 was continuously on to decrease the amount ofparticulate in the air. A diagnostic module 1024 may compare theexpected period for the filter 104, when new, to mitigate particulatedown to the clean level with the measured mitigation period when themitigation module 1004 turns off the circulator blower 108. Thediagnostic module 1024 may determine an amount that the filter 104 isfilled based on the comparison. The diagnostic module 1024 may determinethe amount that the filter 104 is filled, for example, based on a lookuptable or an equation that relates measured mitigation periods to filledamounts of the filter 104 given the expected period for the filter whennew. The lookup table or equation may be calibrated to increase theamount that the filter 104 is filled as the measured mitigation periodincreases and vice versa.

As the filter 104 accumulates particulate over time, based on thecomparison, the diagnostic module 1024 may display an indicator on thecustomer device 524 whether the filter 104 should be replaced based on apredetermined amount of particulate accumulation. For example, thediagnostic module 1024 may display the indicator to replace the filter104 when the measured mitigation period when the mitigation module 1004turns off the circulator blower 108 is greater than the expected periodfor the filter 104, when new, by at least a predetermined amount such astwo or three times the expected period or X minutes, where X is aninteger greater than zero. For example, the expected period for newfilter may be 40 minutes while the period for a filter near end of lifemay be 120 minutes (3 times longer). While the examples of two and threetimes the expected period are provided, another predetermined amount maybe used. The diagnostic module 1024 may display an indicator thatreplacement of the filter 104 is not needed when the measured mitigationperiod when the mitigation module 1004 turns off the circulator blower108 is not greater than the expected period for the filter 104, whennew, by at least the predetermined amount.

In various implementations, the diagnostic module 1024 may determine apredicted period until the filter 104 should be replaced based on themeasured mitigation period when the mitigation module 1004 turns off thecirculator blower 108. For example, the diagnostic module 1024 maydecrease the predicted period as the measured mitigation periodincreases toward a predetermined replacement period. The predeterminedreplacement period may be set based on the expected period and thepredetermined amount. The diagnostic module 1024 may display thepredicted period on the customer device 524. The diagnostic module 1024may display the indicator to replace the filter 104 when the expectedperiod is less than or equal to a predetermined value, such as zero.

FIG. 14 includes an example graph of particulate matter (PM) overtime.FIG. 14 includes an example particulate trace 1404 for a firstmitigation event of particulate matter (PM) when the filter 104 is newand clean, such as shortly after installation or replacement of thefilter 104. FIG. 14 also include an example particulate trace 1408 for asecond mitigation event of particulate when the filter 104 is filled fora long period and needs replacement. As illustrated, the measuredmitigation period of the second mitigation event is longer than themeasured mitigation period of the first mitigation event.

Referring again to FIG. 10, from a first mitigation event of a parameterto a next mitigation event of the parameter, assuming that themitigation events are of a same magnitude and length (of parameterproduction), the measured mitigation period should not varysignificantly. However, all mitigation events do not have the samemagnitude and/or length. For example, one candle being lit for a shortamount of time may provide for a shorter mitigation event (a mitigationevent having a shorter measured mitigation period) than a longer cookingevent (which will have a longer measured mitigation period).

FIG. 15 includes an example graph of particulate matter (PM) overtime.FIG. 15 includes example particulate traces 1504 and 1508 for first andsecond mitigation events of particulate when the filter 104 isapproximately the same level of filled/cleanliness. The particulatetrace 1504 corresponds to a shorter mitigation event, such as for acandle being lit. The particulate trace 1508 corresponds to a longermitigation event, such as for cooking.

Areas G1 and G2 under the traces 1504 and 1508 in FIG. 15 represent theamount of particulates during the event generation phase correspondingto the traces 1504 and 1508, respectively. Areas M1 and M2 under thetraces 1504 and 1508 in FIG. 15 represent the amount of particulatesmitigated during the event mitigation phases corresponding to the traces1504 and 1508, respectively. When G2 is greater than G1, M2 should alsobe greater than M1. The relationship between the area G and the area Mof a mitigation event, the relationship between the area G of amitigation event and the area G of another mitigation event, and/or therelationship between the area M of a mitigation event and the area M ofanother mitigation event can be used to classify the event type and theseverity.

Referring back to FIG. 10, an event module 1028 classifies a mitigationevent as a type of a mitigation event based on the measured mitigationperiod when the mitigation module 1004 shuts the mitigation device(s)off. The event module 1028 may classify each mitigation event.

For example, the event module 1028 may classify a mitigation event as afirst type of mitigation event when the measured mitigation period whenthe mitigation module 1004 shuts the mitigation device(s) off is lessthan a first predetermined period. The event module 1028 may classify amitigation event as a second type of mitigation event when the measuredmitigation period is greater than a second predetermined period that isgreater than the first predetermined period. The event module 1028 mayclassify a mitigation event as a third type of mitigation event when themeasured mitigation period is greater than the first predeterminedperiod and less than the second predetermined period. While the exampleof three different types of mitigation events is provided, a greater orfewer number of types are possible.

As another example, the event module 1028 may classify a mitigationevent as a type of mitigation event when a profile of the decrease inthe IAQ parameter matches a predetermined profile associated with thetype of mitigation event. A different predetermined profile may bestored for each different type of mitigation event. The event module1028 may classify the mitigation event as the one of the types ofmitigation events associated with the one of the predetermined profilesthat most closely matches the profile of the IAQ parameter during themitigation event.

The event module 1028 stores the classifications in memory. The customerdevice 524 may display the classified type of a mitigation event inassociation with that data.

FIG. 16 includes a flowchart depicting an example method of controllingmitigation of an IAQ parameter, such as the amount of particulate, theamount of carbon dioxide, or the amount of VOCs. Control begins with1604 where the mitigation module 1004 receives the IAQ parameter and theclean level for the IAQ parameter. The clean module 1012 determines theclean level for the IAQ parameter based on the values of the IAQparameter while mitigation of the IAQ parameter was off during the lastpredetermined period, such as the last 24 hours prior to the presenttime.

At 1608, the thresholds module 1008 determines the first and second ONthresholds and the OFF threshold for the IAQ parameter. The thresholdsmodule 1008 determines the first ON threshold for the IAQ parameterbased on the clean level and the ON predetermined amount. The thresholdsmodule 1008 sets the second ON threshold to the predetermined value. Thethresholds module 1008 sets the OFF threshold for the IAQ parameterbased on the OFF predetermined amount and the greater one of the firstand second ON thresholds for the IAQ parameter.

At 1612, the mitigation module 1004 determines whether the mitigationdevice(s) for the IAQ parameter is(are) OFF. If 1612 is true, controlcontinues with 1616. If 1612 is false, control transfers to 1624, whichis discussed further below.

At 1616, the mitigation module 1004 determines whether the IAQ parameteris greater than both of the first and second ON thresholds for the IAQparameter. If 1616 is true, the mitigation module 1004 turns themitigation device(s) for the IAQ parameter ON at 1620, and controlreturns to 1604. If 1616 is false, the mitigation module 1004 maintainsthe mitigation device(s) for the IAQ parameter OFF, and control returnsto 1604.

At 1624 (when the mitigation device(s) is(are) ON), the mitigationmodule 1004 determines whether the IAQ parameter is less than the OFFthreshold for the IAQ parameter and at least one of the OFF conditionsare satisfied. If 1624 is true, the mitigation module 1004 turns themitigation device(s) off at 1628 and control returns to 1604. If 1624 isfalse, the mitigation module 1004 maintains the mitigation device(s) on,and control returns to 1604.

FIG. 17 includes a flowchart depicting an example method of indicatingwhether to replace the filter 104 of the circulator blower 108. Controlbegins with 1704 where the time to capacity module 1016 determines theexpected period of particulate mitigation events when the filter 104 isnew, as described above. At 1708, the mitigation module 1004 receivesthe amount of particulate in the air. At 1712, the mitigation module1004 determines whether the circulator blower 108 is presently off forparticulate mitigation. If 1712 is true, control continues with 1716. If1712 is false, control transfers to 1724, which is discussed furtherbelow.

At 1716, the mitigation module 1004 determines whether to turn thecirculator blower 108 ON to mitigate the amount of particulate in theair, as discussed above. If 1716 is true, the mitigation module 1004turns the circulator blower 108 ON at 1720. The timer module 1020 alsoresets the measured mitigation period and starts the measured mitigationperiod. The measured mitigation period increases as time passes. Controlreturns to 1708. If 1716 is false, the mitigation module 1004 maintainsthe circulator blower 108 off, and control returns to 1708.

At 1724, the mitigation module 1004 determines whether to turn thecirculator blower 108 OFF to stop mitigating particulate, as discussedabove. If 1724 is true, control continues with 1728. If 1724 is false,the mitigation module 1004 leaves the circulator blower 108 ON, andcontrol returns to 1708.

At 1728, the mitigation module 1004 turns the circulator blower 108 OFF,and the timer module 1020 stops the measured mitigation period. At 1732,the diagnostic module 1024 determines whether the measured mitigationperiod is greater than the expected period by at least the predeterminedamount. If 1732 is true, the diagnostic module 1024 generates theindicator to replace the filter 104 of the circulator blower 108 at1740, and control returns to 1708. For example, the diagnostic module1024 may set the indicator to a first state. If 1732 is false, thediagnostic module 1024 generates the indicator to indicate thatreplacement of the filter 104 is not yet needed at 1736, and controlreturns to 1708. For example, the diagnostic module 1024 may set theindicator to a second state.

FIG. 18 includes a flowchart depicting an example method of classifyingmitigation events. Control begins with 1804 where the time to capacitymodule 1016 determines the expected period of a mitigation event (e.g.,a particulate mitigation event, a VOC mitigation event, or a carbondioxide mitigation event) of an IAQ parameter (e.g., particulate, VOCs,or carbon dioxide), as described above. At 1808, the mitigation module1004 receives the IAQ parameter.

At 1812, the mitigation module 1004 determines whether the mitigationdevice(s) that mitigate the IAQ parameter are OFF for mitigation of thatIAQ parameter. If 1812 is true, control continues with 1816. If 1812 isfalse, control transfers to 1824, which is discussed further below.

At 1816, the mitigation module 1004 determines whether to turn on themitigation device(s) associated with the IAQ parameter to mitigate thatIAQ parameter, as discussed above. If 1816 is true, the mitigationmodule 1004 turns on the mitigation device(s) at 1820. The timer module1020 also resets the measured mitigation period and starts the measuredmitigation period. The measured mitigation period increases as timepasses. Control returns to 1808. If 1816 is false, the mitigation module1004 maintains the mitigation device(s) off and control returns to 1808.

At 1824, the mitigation module 1004 determines whether to turn themitigation device(s) OFF to stop mitigating the IAQ parameter, asdiscussed above. If 1824 is true, control continues with 1828. If 1824is false, the mitigation module 1004 leaves the mitigation device(s) ON,and control returns to 1808.

At 1828, the mitigation module 1004 turns the mitigation device(s)associated with the IAQ parameter ON, and the timer module 1020 stopsthe measured mitigation period. At 1832, the event module 1028determines the classification for the mitigation event based on themeasured mitigation period, as discussed above. The event module 1028stores the classification in memory.

FIG. 21 includes a block diagram of an example implementation of amitigation system using the example of the thermostat 208. While theexample of the thermostat 208 is provided for purposes of discussion,the modules of the thermostat 208 may alternatively be implementedwithin the IAQ control module 404 or within a combination of thethermostat 208 and the IAQ control module 404.

A temperature difference module 2104 may determine a temperaturedifference within the building based on a difference between: (i) ahighest temperature measured by one of the IAQ sensor modules and thethermostat 208; and (ii) a lowest temperature measured by one of the IAQsensor modules and the thermostat 208. This provides a greatestdifference in temperature between different locations where temperatureis measured within the building. For example, the temperature differencemodule 2104 may set the temperature difference based on or equal to (i)minus (ii).

A baseline module 2108 determines baseline values (Baselines) for theIAQ parameters. For example, the baseline module 2108 may determine abaseline value of the temperature difference, a baseline high RH, abaseline low RH, a baseline amount of particulate, a baseline amount ofVOCs, and a baseline amount of carbon dioxide.

The baseline module 2108 may determine the baseline values, for example,based on an average (e.g., non-weighted) of the respective IAQparameters over a last predetermined window period before the presenttime. The predetermined window period may be calibratable and may be,for example, a week, a month, or another suitable period. For example,the baseline module 2108 may set the baseline temperature differencebased on or equal to an average of all of the temperature differencesover the last predetermined window period before the present time. Thebaseline module 2108 may set a baseline mid RH based on or equal to anaverage of all of the RHs measured using the RH sensor 312 over the lastpredetermined window period before the present time. The baseline module2108 may set the baseline high RH based on or equal to the baseline midRH plus a predetermined RH. The baseline module 2108 may set thebaseline low RH based on or equal to the baseline mid RH minus thepredetermined RH.

The baseline module 2108 may set the baseline amount of particulatebased on or equal to an average of the amounts of particulate measuredusing the particulate sensor 316 over the last predetermined windowperiod before the present time. In the example of the baseline amount ofparticulate, the baseline module 2108 may filter out (from theaveraging) amounts of particulate measured by the particulate sensor 316during excursions.

The baseline module 2108 may set the baseline amount of carbon dioxidebased on or equal to an average of the amounts of carbon dioxidemeasured using the carbon dioxide sensor 324 over the last predeterminedwindow period before the present time. In the example of the baselineamount of carbon dioxide, the baseline module 2108 may filter out (fromthe averaging) amounts of carbon dioxide measured by the carbon dioxidesensor 324 during excursions.

The baseline module 2108 may set the baseline amount of VOCs based on orequal to an average of the amounts of VOCs measured using the VOC sensor320 over the last predetermined window period before the present time.In the example of the baseline amount of VOCs, the baseline module 2108may filter out (from the averaging) amounts of carbon dioxide measuredby the carbon dioxide sensor 324 during excursions. The baseline valuestherefore correspond to normalized values of the respective IAQparameters within the building.

FIG. 22 includes example graphs of amounts of particulate, amounts ofVOCs, and amounts of carbon dioxide over time. Some example excursionsare circled. The baseline module 2108 may identify excursions based onthe existence of a magnitude of a rate of change (e.g., betweenconsecutive values) that is greater than a predetermined rate of change.Excursions may include values between when a magnitudes of rate ofchange is greater than the predetermined rate of change and when the IAQparameters returns to the baseline values.

Referring back to FIG. 21, a control module 2112 selectively enables,disables, and resets areas determined by an area module 2116. The areamodule 2116 determines areas between respective curves of the IAQparameters and the respective baseline value for each of the IAQparameters. For example, the area module 2116 determines an area betweena curve formed by the temperature difference and the baselinetemperature difference. The area module 2116 determines an area betweena high RH curve formed by the RH and the baseline high RH. The areamodule 2116 determines an area between a low RH curve formed by the RHand the baseline low RH. The area module 2116 determines an area betweena curve formed by the amount of particulate and the baseline amount ofparticulate. The area module 2116 determines an area between a curveformed by the amount of VOCs and the baseline amount of VOCs. The areamodule 2116 determines an area between a curve formed by the amount ofcarbon dioxide and the baseline amount of carbon dioxide.

2116 The control module 2112 may enable an area calculation for one ofthe IAQ parameters, for example, when the one of the IAQ parameters isgreater than a respective predetermined value (or threshold). Forexample, the control module 2112 may enable the area calculation for thetemperature difference when the temperature difference is greater than apredetermined temperature difference. The control module 2112 may enablethe area calculation for high RH when the RH is greater than the thirdpredetermined RH. The control module 2112 may enable the areacalculation for low RH when the RH is less than the first predeterminedRH. The control module 2112 may enable the area calculation forparticulate matter when the amount of particulate matter is greater thanthe predetermined amount of particulate matter. The control module 2112may enable the area calculation for VOCs when the amount of VOCs isgreater than the predetermined amount of VOCs. The control module 2112may enable the area calculation for carbon dioxide when the amount ofcarbon dioxide is greater than the predetermined amount of carbondioxide.

In various implementations, to enable the area calculation for one ofthe IAQ parameters, the control module 2112 may also require a rate ofchange (ROC) of the one of the IAQ parameters to be greater than apredetermined enabling ROC that is greater than zero. The control module2112 may disable the area calculation for one of the IAQ parameters, forexample, when the ROC of the one of the IAQ parameters is less than thepredetermined enabling ROC. The control module 2112 may reset the areacalculation for one of the IAQ parameters, for example, when the one ofthe IAQ parameters is less than the respective baseline value or lessthan the respective baseline value (continuously) for at least apredetermined reset period. This may be performed for each of the IAQparameters. In the example of RH, the control module 2112 may reset thearea calculation for low RH when the RH is greater than the baseline lowRH value or greater than the baseline low RH value (continuously) for atleast a predetermined reset period.

When the area of one of the IAQ parameters is greater than apredetermined mitigation value, a mitigation module 2120 operates one ormore of the mitigation devices 424 to adjust (e.g., decrease or increasein the example of low RH) that one of the IAQ parameters. For example,the mitigation module 2120 may turn the air cleaner/purifier 428 on whenthe area for particulate is greater than a predetermined particulatemitigation value. The mitigation module 2120 may leave the aircleaner/purifier 428 on until the amount of particulate measured by theparticulate sensor 316 is less than the second predetermined amount ofparticulate. The mitigation module 2120 may turn the aircleaner/purifier 428 off when the amount of particulate measured by theparticulate sensor 316 is less than the second predetermined amount ofparticulate. In various implementations, the mitigation module 2120 mayvary the speed of the air cleaner/purifier 428 based on the amount ofparticulate measured by the particulate sensor 316. For example, themitigation module 2120 may increase the speed of the aircleaner/purifier 428 as the amount of particulate (or the area under thecurve) increases and vice versa.

The mitigation module 2120 may turn the humidifier 432 on when the areafor low RH is greater than a predetermined low RH mitigation value. Themitigation module 2120 may leave the humidifier 432 on until the RHmeasured by the RH sensor 312 is greater than the second predeterminedRH. The mitigation module 2120 may turn the humidifier 432 off when theRH measured by the RH sensor 312 is greater than the secondpredetermined RH.

The mitigation module 2120 may turn the dehumidifier 436 on when thearea for high RH is greater than a predetermined high RH mitigationvalue. The mitigation module 2120 may leave the dehumidifier 436 onuntil the RH measured by the RH sensor 312 is less than the fourthpredetermined RH. The mitigation module 2120 may turn the dehumidifier436 off when the RH measured by the RH sensor 312 is less than thefourth predetermined RH.

The mitigation module 2120 may turn the ventilator 440 on when the areafor VOCs is greater than a predetermined VOCs mitigation value. Themitigation module 2120 may leave the ventilator 440 on until the amountof VOCs measured by the VOC sensor 320 is less than the secondpredetermined amount of VOCs. The mitigation module 2120 may turn theventilator 440 off when the amount of VOCs measured by the VOC sensor320 is less than the second predetermined amount of VOCs.

As another example, the mitigation module 2120 may turn the ventilator440 on when the area for carbon dioxide is greater than a predeterminedcarbon dioxide mitigation value. The mitigation module 2120 may leavethe ventilator 440 on until the amount of carbon dioxide measured by thecarbon dioxide sensor 324 is less than the second predetermined amountof carbon dioxide. The mitigation module 2120 may turn the ventilator440 off when the amount of carbon dioxide measured by the carbon dioxidesensor 324 is less than the second predetermined amount of carbondioxide.

When two or more of the areas are greater than the respectivepredetermined mitigation values, the mitigation module 2120 may mitigatethe respective IAQ parameters, for example, in order according to theprioritization or in order of occurrence.

Using the areas (instead of comparisons of the IAQ values with therespective predetermined values) to trigger turning on of one or more ofthe mitigation devices 424 may decrease a possibility of mitigation,alerting, etc. in response to IAQ sensor noise and/or error. This maymaintain or enhance user trust in the system. Under some circumstances,however, the presence of simultaneous rises in two or more of the IAQparameters may be indicative of an actionable mitigation event and notIAQ sensor noise and/or error. The mitigation module 2120 may therefore(even when all of the areas are less than the respective predeterminedmitigation values) operate one or more of the mitigation devices 424when two or more of the IAQ parameters simultaneously increase above therespective predetermined values.

FIG. 23 includes example graphs of temperature, RH, particulate, VOCs,and carbon dioxide over time. Concurrent rises in RH, amount ofparticulate, and amount of VOCs are present during period 2304.Concurrent rises in temperature, RH, amount of VOCs, and amount ofcarbon dioxide are present during period 2308.

Concurrent rises in more than two parameters are not as likely to beattributable to sensor noise and/or error. The mitigation module 2120may therefore operate one or more of the mitigation devices 424 when twoor more of the parameters are concurrently greater than the respectivepredetermined values. The mitigation module 2120 may mitigate therespective IAQ parameters, for example, in order according to theprioritization or in order according to when the IAQ parameters becamegreater than the respective predetermined values.

FIG. 24 includes a flowchart depicting an example method of mitigatingIAQ parameters. Control begins with 2404 when the mitigation devices 424are off. At 2404, the thermostat 208 may determine whether one or moreof the IAQ parameters are greater than (or less than) the respectivepredetermined value (or threshold).

For example, the control module 2112 may determine whether thetemperature difference is greater than the predetermined temperaturedifference. The predetermined temperature difference may be calibratableand may be set to, for example, approximately 2° F. or another suitabletemperature. The control module 2112 may also determine whether the RHis greater than the third predetermined RH. The third predetermined RHmay be calibratable and may be set to, for example, approximately 50percent RH or another suitable value. The control module 2112 may alsodetermine whether the RH is less than the first predetermined RH. Thefirst predetermined RH is less than the third predetermined RH. Thefirst predetermined RH may be calibratable and may be set to, forexample, approximately 40 percent RH or another suitable value. Thecontrol module 2112 may also determine whether the amount of particulatematter is greater than the predetermined amount of particulate matter.The predetermined amount of particulate may be calibratable and may beset to, for example, approximately 12 μg/cubic meter or another suitablevalue. The control module 2112 may also determine whether the amount ofVOCs is greater than the predetermined amount of VOCs. The predeterminedamount of VOCs may be calibratable and may be set to, for example,approximately 500 ppb or another suitable value. The control module 2112may also determine whether the amount of carbon dioxide is greater thanthe predetermined amount of carbon dioxide. The predetermined amount ofcarbon dioxide may be calibratable and may be set to, for example,approximately 1000 ppm or another suitable value. If 2404 is false, thecontrol module 2112 may reset the areas determined by the area module2116 and maintain the mitigation devices 424 off at 2408. Control mayreturn to 2404. If 2404 is true, control may continue with 2412.

In various implementations, if the amount of particulate is greater thanthe predetermined amount of particulate, the control module 2112 mayalso determine whether the amount of particulate in the air outside thebuilding is greater than the predetermined amount of particulate. If so,(and no other IAQ parameters are greater than or less than therespective predetermined values, control may transfer to 2408, asdiscussed above. If not, control may continue with 2412. The local dataserver 520 determines the amount of particulate in the air outside thebuilding based on the geographical location of the building.

At 2412, the control module 2112 may determine whether the ROC(s) of theone(s) of the IAQ parameters (that are/were greater than or less thanthe respective predetermined values) is/are greater than thepredetermined ROCs. For example, if the amount of particulate wasgreater than the predetermined amount of particulate and the amount ofcarbon dioxide was greater than the predetermined amount of carbondioxide, the control module 2112 may determine whether the ROC of theamount of particulate is greater than a predetermined ROC of particulateand whether the ROC of the amount of carbon dioxide is greater than apredetermined ROC of carbon dioxide. Magnitudes of ROCs may be used invarious implementations. If 2412 is true, control may continue with2424, which is discussed further below. If 2412 is false, control maytransfer to 2416.

At 2416, the control module 2112 may determine whether the ROC(s) of theone(s) of the IAQ parameters (that are/were greater than or less thanthe respective predetermined values) is/are less than the predeterminedROCs (e.g., continuously for at least a predetermined period). Forexample, if the amount of particulate was greater than the predeterminedamount of particulate and the amount of carbon dioxide was greater thanthe predetermined amount of carbon dioxide, the control module 2112 maydetermine whether the ROC of the amount of particulate is less than thepredetermined ROC of particulate and whether the ROC of the amount ofcarbon dioxide is less than the predetermined ROC of carbon dioxide.Magnitudes of ROCs may be used.

If 2416 is true, the control module 2112 may reset the areas of theone(s) of the IAQ parameters (that are/were greater than or less thanthe respective predetermined values) and 2408. The mitigation module2120 may also turn off ones of the mitigation devices 424 in use tomitigate the IAQ parameters (that are/were greater than or less than therespective predetermined values) at 2408. If 2416 is false, the areamodule 2116 may maintain or decrement the area(s) at 2420, and controlmay return to 2404. The mitigation module 2120 may maintain ones of themitigation devices 424 in use to mitigate the IAQ parameters (thatare/were greater than or less than the respective predetermined values)at 2420.

At 2424, the control module 2112 enables and updates the areacalculations for the one or more of the IAQ parameters that are greaterthan or less than the respective predetermined values. The area module2116 determines the area(s) for the one or more of the IAQ parametersthat are greater than or less than the respective predetermined values.The area module 2116 determines the areas for the IAQ parameters basedon the IAQ parameters and the baseline values, respectively.

At 2428, the mitigation module 2120 determines whether two or more ofthe IAQ parameters simultaneously or approximately simultaneously (e.g.,within a predetermined period) rose (e.g., had ROCs that are greaterthan the respective predetermined ROCs). If 2428 is true, the mitigationmodule 2120 turns on one or more of the mitigation devices 424 at 2436to mitigate those two or more IAQ parameters to less than (or greaterthan in the case of low RH) the respective predetermined values. Invarious implementations, the mitigation module 2120 may mitigate the twoor more IAQ parameters according to the prioritization. If 2428 isfalse, control may transfer to 2432. A likelihood of the occurrence ofsimultaneous or approximately simultaneous rises in two or more of theIAQ parameters may be low. Therefore, the mitigation module 2120 mayturn on one or more of the mitigation devices 424, even though the areasmay be less than the predetermined mitigation values.

At 2432, the mitigation module 2120 determines whether one or more ofthe area(s) are greater than the predetermined mitigation values. If2432 is false, the mitigation module 2120 may return to 2404 and notturn on one, more than one, or any of the mitigation devices 424. If2432 is true, the mitigation module 2120 may turn on one or more of themitigation devices 424 at 2436 to mitigate the associated two or moreIAQ parameters to less than (or greater than in the case of low RH) therespective predetermined values. Because mitigation is started when thearea(s) are greater than the predetermined mitigation value(s), themitigation module 2120 may avoid improperly beginning mitigation orissuing an alert in response to simply an IAQ parameter being greaterthan or less than a threshold. This may improve user experience andperception of the system as a whole.

The foregoing description is merely illustrative in nature and is in noway intended to limit the disclosure, its application, or uses. Thebroad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent upon a study of the drawings, thespecification, and the following claims. It should be understood thatone or more steps within a method may be executed in different order (orconcurrently) without altering the principles of the present disclosure.Further, although each of the embodiments is described above as havingcertain features, any one or more of those features described withrespect to any embodiment of the disclosure can be implemented in and/orcombined with features of any of the other embodiments, even if thatcombination is not explicitly described. In other words, the describedembodiments are not mutually exclusive, and permutations of one or moreembodiments with one another remain within the scope of this disclosure.

Spatial and functional relationships between elements (for example,between modules, circuit elements, semiconductor layers, etc.) aredescribed using various terms, including “connected,” “engaged,”“coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and“disposed.” Unless explicitly described as being “direct,” when arelationship between first and second elements is described in the abovedisclosure, that relationship can be a direct relationship where noother intervening elements are present between the first and secondelements, but can also be an indirect relationship where one or moreintervening elements are present (either spatially or functionally)between the first and second elements. As used herein, the phrase atleast one of A, B, and C should be construed to mean a logical (A OR BOR C), using a non-exclusive logical OR, and should not be construed tomean “at least one of A, at least one of B, and at least one of C.”

In the figures, the direction of an arrow, as indicated by thearrowhead, generally demonstrates the flow of information (such as dataor instructions) that is of interest to the illustration. For example,when element A and element B exchange a variety of information butinformation transmitted from element A to element B is relevant to theillustration, the arrow may point from element A to element B. Thisunidirectional arrow does not imply that no other information istransmitted from element B to element A. Further, for information sentfrom element A to element B, element B may send requests for, or receiptacknowledgements of, the information to element A.

In this application, including the definitions below, the term “module”or the term “controller” may be replaced with the term “circuit.” Theterm “module” may refer to, be part of, or include: an ApplicationSpecific Integrated Circuit (ASIC); a digital, analog, or mixedanalog/digital discrete circuit; a digital, analog, or mixedanalog/digital integrated circuit; a combinational logic circuit; afield programmable gate array (FPGA); a processor circuit (shared,dedicated, or group) that executes code; a memory circuit (shared,dedicated, or group) that stores code executed by the processor circuit;other suitable hardware components that provide the describedfunctionality; or a combination of some or all of the above, such as ina system-on-chip.

The module may include one or more interface circuits. In some examples,the interface circuits may include wired or wireless interfaces that areconnected to a local area network (LAN), the Internet, a wide areanetwork (WAN), or combinations thereof. The functionality of any givenmodule of the present disclosure may be distributed among multiplemodules that are connected via interface circuits. For example, multiplemodules may allow load balancing. In a further example, a server (alsoknown as remote, or cloud) module may accomplish some functionality onbehalf of a client module.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes, datastructures, and/or objects. The term shared processor circuitencompasses a single processor circuit that executes some or all codefrom multiple modules. The term group processor circuit encompasses aprocessor circuit that, in combination with additional processorcircuits, executes some or all code from one or more modules. Referencesto multiple processor circuits encompass multiple processor circuits ondiscrete dies, multiple processor circuits on a single die, multiplecores of a single processor circuit, multiple threads of a singleprocessor circuit, or a combination of the above. The term shared memorycircuit encompasses a single memory circuit that stores some or all codefrom multiple modules. The term group memory circuit encompasses amemory circuit that, in combination with additional memories, storessome or all code from one or more modules.

The term memory circuit is a subset of the term computer-readablemedium. The term computer-readable medium, as used herein, does notencompass transitory electrical or electromagnetic signals propagatingthrough a medium (such as on a carrier wave); the term computer-readablemedium may therefore be considered tangible and non-transitory.Non-limiting examples of a non-transitory, tangible computer-readablemedium are nonvolatile memory circuits (such as a flash memory circuit,an erasable programmable read-only memory circuit, or a mask read-onlymemory circuit), volatile memory circuits (such as a static randomaccess memory circuit or a dynamic random access memory circuit),magnetic storage media (such as an analog or digital magnetic tape or ahard disk drive), and optical storage media (such as a CD, a DVD, or aBlu-ray Disc).

The apparatuses and methods described in this application may bepartially or fully implemented by a special purpose computer created byconfiguring a general purpose computer to execute one or more particularfunctions embodied in computer programs. The functional blocks,flowchart components, and other elements described above serve assoftware specifications, which can be translated into the computerprograms by the routine work of a skilled technician or programmer.

The computer programs include processor-executable instructions that arestored on at least one non-transitory, tangible computer-readablemedium. The computer programs may also include or rely on stored data.The computer programs may encompass a basic input/output system (BIOS)that interacts with hardware of the special purpose computer, devicedrivers that interact with particular devices of the special purposecomputer, one or more operating systems, user applications, backgroundservices, background applications, etc.

The computer programs may include: (i) descriptive text to be parsed,such as HTML (hypertext markup language), XML (extensible markuplanguage), or JSON (JavaScript Object Notation) (ii) assembly code,(iii) object code generated from source code by a compiler, (iv) sourcecode for execution by an interpreter, (v) source code for compilationand execution by a just-in-time compiler, etc. As examples only, sourcecode may be written using syntax from languages including C, C++, C#,Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl,Pascal, Curl, OCaml, Javascript®, HTML5 (Hypertext Markup Language 5threvision), Ada, ASP (Active Server Pages), PHP (PHP: HypertextPreprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, VisualBasic®, Lua, MATLAB, SIMULINK, and Python®.

What is claimed is:
 1. An indoor air quality (IAQ) system for abuilding, comprising: an IAQ sensor module that is located within thebuilding and that comprises at least one of: a temperature sensorconfigured to measure a temperature of air at the IAQ sensor module; arelative humidity (RH) sensor configured to measure a RH of the air atthe IAQ sensor module; a particulate sensor configured to measure anamount of particulate of at least a predetermined size present in theair at the IAQ sensor module; a volatile organic compound (VOC) sensorconfigured to measure an amount of VOCs present in the air at the IAQsensor module; and a carbon dioxide sensor configured to measure anamount of carbon dioxide present in the air at the IAQ sensor module;and at least one of a thermostat and an IAQ control module configuredto, in response to a determination that one of the temperature, the RH,the amount of particulate, the amount of VOCs, and the amount of carbondioxide is greater than a predetermined value while one of a pluralityof mitigation devices is off: calculate a value of an area between: abaseline value; and a curve formed by the one of the temperature, theRH, the amount of particulate, the amount of VOCs, and the amount ofcarbon dioxide; and turn on the one of the plurality of mitigationdevices when the value of the area is greater than a predeterminedvalue.
 2. The IAQ system of claim 1 wherein the mitigation devicesinclude at least two of: an air handler unit of a heating, ventilation,and air conditioning (HVAC) system a blower of an air handler unit ofthe HVAC system of the building; a condenser unit of the HVAC system ofthe building; an air purifier configured to receive power via a standardwall outlet and to filter particulate from air within the building; ahumidifier configured to humidify air within the building; adehumidifier configured to dehumidify air within the building; and aventilator configured to vent air out of the building from within thebuilding.
 3. The IAQ system of claim 1 wherein the at least one of thethermostat and the IAQ control module is configured to maintain the oneof the plurality of mitigation devices off when the value of the area isless than the predetermined value.
 4. The IAQ system of claim 1 whereinthe at least one of the thermostat and the IAQ control module isconfigured to selectively turn on the one of the plurality of mitigationdevices when at least two of the temperature, the RH, the amount ofparticulate, the amount of VOCs, and the amount of carbon dioxide aregreater than respective predetermined values.
 5. The IAQ system of claim4 wherein the at least one of the thermostat and the IAQ control moduleis configured to maintain the one of the plurality of mitigation devicesoff when: only one of the temperature, the RH, the amount ofparticulate, the amount of VOCs, and the amount of carbon dioxide isgreater than the predetermined value; and the value of the area is lessthan a predetermined value.
 6. The IAQ system of claim 1 wherein the atleast one of the thermostat and the IAQ control module is configured toselectively turn on at least one of the plurality of mitigation deviceswhen: at least two of the temperature, the RH, the amount ofparticulate, the amount of VOCs, and the amount of carbon dioxide aregreater than respective predetermined values; and the value of the areais less than a predetermined value.
 7. The IAQ system of claim 1 whereinthe at least one of the thermostat and the IAQ control module isconfigured to selectively turn on at least one of the plurality ofmitigation devices when at least three of the temperature, the RH, theamount of particulate, the amount of VOCs, and the amount of carbondioxide are greater than respective predetermined values.
 8. A method,comprising: at least one of: by a temperature sensor of an indoor airquality (IAQ) sensor module within a building, measuring a temperatureof air at the IAQ sensor module; by a relative humidity (RH) sensor ofthe IAQ sensor module within the building, measuring a RH of the air atthe IAQ sensor module; by a particulate sensor of the IAQ sensor modulewithin the building, measuring an amount of particulate of at least apredetermined size present in the air at the IAQ sensor module; by avolatile organic compound (VOC) sensor of the IAQ sensor module withinthe building, measuring an amount of VOCs present in the air at the IAQsensor module; and by a carbon dioxide sensor of the IAQ sensor modulewithin the building, measuring an amount of carbon dioxide present inthe air at the IAQ sensor module; and in response to a determinationthat one of the temperature, the RH, the amount of particulate, theamount of VOCs, and the amount of carbon dioxide is greater than apredetermined value while one of a plurality of mitigation devices isoff: calculating a value of an area between: a baseline value; and acurve formed by the one of the temperature, the RH, the amount ofparticulate, the amount of VOCs, and the amount of carbon dioxide; andturning on the one of the plurality of mitigation devices when the valueof the area is greater than a predetermined value.
 9. The method ofclaim 8 wherein the mitigation devices include at least two of: an airhandler unit of a heating, ventilation, and air conditioning (HVAC)system a blower of an air handler unit of the HVAC system of thebuilding; a condenser unit of the HVAC system of the building; an airpurifier configured to receive power via a standard wall outlet and tofilter particulate from air within the building; a humidifier configuredto humidify air within the building; a dehumidifier configured todehumidify air within the building; and a ventilator configured to ventair out of the building from within the building.
 10. The method ofclaim 9 further comprising maintaining the one of the plurality ofmitigation devices off when the value of the area is less than thepredetermined value.
 11. The method of claim 8 wherein selectivelyturning on the one of the plurality of mitigation devices includesselectively turning on the one of the plurality of mitigation deviceswhen at least two of the temperature, the RH, the amount of particulate,the amount of VOCs, and the amount of carbon dioxide are greater thanrespective predetermined values.
 12. The method of claim 11 furthercomprising maintaining the one of the plurality of mitigation devicesoff when: only one of the temperature, the RH, the amount ofparticulate, the amount of VOCs, and the amount of carbon dioxide isgreater than the predetermined value; and the value of the area is lessthan a predetermined value.
 13. The method of claim 8 whereinselectively turning on the one of the plurality of mitigation devicesincludes selectively turning on at least one of the plurality ofmitigation devices when: at least two of the temperature, the RH, theamount of particulate, the amount of VOCs, and the amount of carbondioxide are greater than respective predetermined values; and the valueof the area is less than a predetermined value.
 14. The method of claim8 wherein selectively turning on the one of the plurality of mitigationdevices includes selectively turning on at least one of the plurality ofmitigation devices when at least three of the temperature, the RH, theamount of particulate, the amount of VOCs, and the amount of carbondioxide are greater than respective predetermined values.